So i've searched and searched the interwebs and have seen some similar issues but nothing that I have seen has been close enough to my specific issue for me to feel comfortable in trusting the thread info.

The car is a stock 99 Mazda protege 4 door 1.6L w/auto trans.

Since I got the car it's been having this problem with the idle where after going from park to either reverse or drive but still parked or stopped the revs will drop from like 700ish to 300 or sometime even as low as what looks like 100-200 rpms but then i will immediately jump back to 700. It will repeat this cycle fairly quickly until I actually begin to accelerate either in drive or reverse and will continue once I stop at a stop light or pull in a drive way etc. There have been hours or sometimes days where this problem will not occur then other days it will do it most of the day.

I bought the car a week ago from a friend and the person he bought it from had it sitting in the garage with a full tank of gas for 3 years without touching it.

When I got it i burned up the whole tank in the first day or so trying to get rid of it so i can refill it with fresh gas. A guy at autozone told me that I should put in Premium gas because of the octane rating it will help burn up some of the possible carbon/crap that may have built up in the engine. Did that and burned through the half tank of premo that I put in it, and now I have a full tank or so of regular unleaded with some fuel injector cleaner that a friend of mine got from the grease monkey that he works at.

Also when I bought the car the air intake hose was dry rotted and almost split in half. I duct taped it for a quick fix and bought a replacement last night which arrived today and has already been installed. I also sprayed out the MAF sensor and the MAF connector on the harness (with the battery unplugged until it dried) with some MAF cleaner. It seems the only difference that the new hose and clean maf sensor gave is that now I actually have some power from 1k to 3k which was painfully slow before cleaning/replacing those items.

I was hoping that replacing the hose and cleaning the MAF sensor would fix the idle issue but unfortunately it didn't do it.

A buddy of mine told me that you can loosen a bold near where the intake hose meets the manifold that controls the idle or something to that effect which I have not done yet as it seems like it is a quick fix but not addressing the underlying issue. But I have been wrong before.

I'm wondering if its the timing that is off? or a bad/dirty MAP or EGR valve? i'm hoping its not as those parts can be expensive.

Also every once in a while I will get a p0106 code but it will go away for a day or so and return. which I know is that MAP sensor. and I'm not sure which order this happens in, but either when the revs drop the lights dim, or when the revs jump back up the lights dim either way the lights dim then brighten inside the car as the revs fluctuate.

If anyone has any input or suggestions it would be greatly appreciated. Thanks in advance.

Sorry about the long post. More info can never hurt. Hopefully atleast

 

It is possible to clean the EGR valve as opposed to replacement.
the MAP sensor functions as a backup input in case of MAF failure. The PCM supplies a 5 Volt reference signal to the MAP sensor. Usually the PCM also supplies a ground circuit to the MAP sensor as well. As the manifold pressure changes with load, the MAP sensor input informs the PCM. At idle the voltage should be 1 to 1.5 Volts and approximately 4.5 Volts at Wide Open Throttle (WOT). The PCM looks for any change in manifold pressure to be preceded by a change in engine load in the form of changes in throttle angle, engine speed, or Exhaust Gas Recirculation (EGR) flow. If the PCM doesn't see any of these factors change while detecting a rapid change in MAP value, it will set a P0106.

Potential Symptoms


The following could be symptomatic of a P0106:

• Engine runs rough
• Black smoke at tailpipe
• Engine will not idle
• Poor fuel economy
• Engine misses at speed

Causes


A P0106 could be caused by:

• Bad MAP sensor
• Water/dirt intrusion affecting MAP sensor connector
• Intermittent open in the reference, ground, or signal wire for the MAP sensor
• Intermittent short in the reference, ground, or signal wire for the MAP sensor
• Ground problem due to corrosion causing intermittent signal problem
• A break in the flexible air intake duct between the MAF and the intake manifold
• Bad PCM (do not assume the PCM is bad until you've exhausted all other possibilities)

Possible Solutions

Using a scan tool, watch the MAP sensor value with the key on, engine off. Compare the BARO reading with the MAP reading. They should be roughly equal. The voltage for the MAP sensor should read approx. 4.5 volts. Now start the engine and look for a significant drop in the MAP sensor voltage indicating the MAP sensor is working.
If the MAP reading doesn't change perform the following:

1. With the Key on, engine off, disconnect the vacuum hose from the MAP sensor. Using a vacuum pump, pull 20 in. of vacuum on the MAP sensor. Does the voltage drop? It should. If it doesn't inspect the MAP sensor vacuum port and vacuum hose to manifold for a restriction of some kind. Repair or replace as necessary.
2. If there are no restrictions, and the value doesn't change with vacuum, then perform the following: with the Key on and engine off and the MAP sensor unplugged, check for 5 Volts at the reference wire to the MAP sensor connector with a Digital Voltmeter. If there is none, check for reference voltage at the PCM connector. If the reference voltage is present at the PCM connector but not the MAP connector, check for open or short in the reference wire between MAP and PCM and retest.
3. If reference voltage is present, then check for existing ground at the MAP sensor connector. If it isn't present then repair open/short in the ground circuit.
4. If ground is present, then replace MAP sensor.

A vacuum leak could still be present. I had an internal brake booster leak that gave me a lean code. If your not getting any other codes don't worry about it.

 

Zed: you are in good hands with Noggin!

Just adding a little: in your situation you may have drawn dirt into the in fuel filter and injectors by using the old gas. Measure the fuel pressure at idle.
Look for the EGR boost sensor on the firewall, passenger side. It really is a MAP senor. Anyway, there is a vacuum tube you need to follow down behind the intake manifold. Pull it off the nipple. Use a 2-3" strong wire and push it in the nipple. If there is any resistance push through it.
EricTheCarGuy has a good video on cleaning an EGR system on Youtube.

 

Run Marvel Mystery oil through the intake to burn off carbon deposits.
I would also clean MAF sensor, EGR valve.

 

good post from Noggin - if that doesnt work buy a cheap OBDII reader off ebay and check your codes. If the cars a high miler it could be an 02 sensor (Lambda, Hego)

 

Guess it's not a Mystery anymore: Marvel Mystery Oil - Walmart.com
It's like Seafoam I guess. Found some quotes from other forums:

"Marvel Mystery Oil -- which is basically a thin, petroleum-based solvent to which red food coloring and perfume has been added -- does seem to have some value in freeing up sticky hydraulic-valve lifters when added to the oil and it almost certainly does no harm."

"Basically it's some oil, mineral spirits, dichlorobenzene (about 0.25%), red dye, and a bit of Wintergreen oil for fragrance.
The military certainly used it by the 55 gallon barrel back in the days of planes with round motors which correlates with your warbird. FAA is reported to have used it in their DC-3s too.
It does seem to help loosen up sludge and such just prior to an oil change (1 pint for about every 6 qts an hour or two prior to change)."

I personally wouldn't rev it past 3500 rpm while this thin stuff is in there (just like Seafoam).

 

Well at least it's a lot cheaper than seafoam.