engine idle questions

Hello,  new to this forum as i am a new Mazda owner.  I sold Mazdas a few years ago at a dealership for a while, and ever since wanted one.  finally got one. 
 
My Mazda:  2006 Mazda 6i 2.0  36,000 miles
 
Question:  While sitting at stoplights or idleing, i can feel the engine shake and vibrate (almost feels like it starts to die but doesnt) about 4 or 5 times and at other times i would describe it as just a rough idle.
 
Any ideas?
 
Some more info:
oil looks good, was just changed the day i got it from the car lot...
i use Shell 87 octain gas
i drive 65+ miles each day to work 1 way, and it is still doing that when i get close to work (engine is good and warmed up for sure by this time!)
doesnt seem to show any patterns as to when it is worse or when it is smoother idleing...
Havent looked at anything else.
 
Another question... in case this needs to be done or someone recommends doing a tune up...
 
What brand/type plugs and wires are recommended in this vehicle?
 
 
Thanks
 
 

Well, you have the 2.3L which I also have and have never found to be the most civilized (smoothest) engine around.  Mine is a bit rough too, more so since the heftier rear mount.  I too use Shell 87 99% of the time.
 
1. If it's an auto, try dropping it into neutral when it does that and see if it improves.
 
2. Also, you might try cleaning the MAF sensor to see if that helps.  Use a non-aerosol (DO NOT use any kind of aerosol or compressed anything on it) like rubbing alcohol and a carefully handled Q-tip to clean it.  Do not rub hard.  Use a light touch as these can be easily damaged.
Have you run the OBDII diagnostics on it to see if there's a code on the ECU?  You might have a rich idle, which could e the O2 sensor.  but really, it could be a number of things.
 
3. And unless the car has 75+K on the clock I wouldn't worry about new plugs.  It shouldn't need them. 
 
4. And as far as new wires are concerned... have you looked?  These cars don't have plug wires in the traditional sense of the meaning.
 
 

Wow... i feel like an idiot.. i posted that when i was at work and was half out of it.  I have a 3i 2.0  not a 6i!  lol.
Sorry about that.

Also feel like an idiot now that i see there are no plug wires... if i put it in neutral it smooths up a lot.

Well, yeah, that does make a bit of a difference, but not much really.
Don't worry about it.  We all have brain-fades, even ME!!  Ask anyone 'round these parts.      They'll be GLAD to highlight the idiot mistakes/farts I've made. Especially a guy named "Uber."  You'll learn more about him as time goes on....   (j/k Ub!!)
As I've said the engine isn't as smooth as say... a Honda VTEC, but who cares. These ain't luxury cars.  They were built to be grocery getter's w/an eye on us economy performance seekers.  It's hard to get a bigger 4-cyl to be smooth, though the 2.3 more fits that bill than the 2.0.
If you bought the car used (I assume you did from your OP) I'd try cleaning the MAF.  See if that helps.  If your careful about it, it couldn't hurt!