Hi... I'm new here so I don't know this forum very well.... but I have lots of experience with engines and performance mods.
I don't know how much experience you have with vehicles... but it sounds limited so I'm not sure which procedures you will be able to do.
I am a little confused about the statement "the diagnosis machine said bad timing. I replaced that last year, so I took it apart and looked at the timing at it was right where it needed to be"
I'm not familiar with the MX-6 yet..... does it use a distributor?
Even if the timing is off the car should still start....
Step 1) Reomve all four spark plug wires ( write on them or use tape to identify which one goes to which plug )
Step 2) Remove the first spark plug in the far right cylinder
Step 3) Look at the spark plug... it should be a nice chocolate brown... not black... and not white ( post a picture if you want me to diagnose how the car is running )
Step 4) Assuming the spark plug is good.... attach it to one spark plug wire... allow the body of the spark plug to sit on a grounded part of the chassis and have someone crank the engine for 2-3 seconds
Step 5) If you see a spark... then it's not a major problem with the ignition
Step 6) Remove spark plug and test the other three wires with the same procedure ensuring that you get a spark from all four wires
The reason you leave the other wires off is incase the engine starts.... which would not be a good situation.... with the wires off the engine can't fire.
Only crank it for a few seconds.... you don't want to flood the engine
If all goes good and you have spark.... the only other problem is fuel.
You should be able to measure the fuel pressure if you have a Schrader valve (looks like a valve from a bicycle)... again.... not familiar with the Mazda engines... so I don't know if you have a Schrader valve.
The tool to measure fuel pressure is fairly cheap.... you should be able to get it off Ebay for under $20
Here is a decent example...
http://cgi.ebay.com/ebaymotors/Fuel-Pressure-Tester-Kit-New-KAL2530-KAL-Equip_W0QQcmdZViewItemQQcategoryZ43989QQihZ018QQitemZ280073370196QQrdZ1 So... if you check your fuel pressure that will let you know if your fuel regulator is working or if there is some other issue such as a blocked/kinked line or a bad fuel pump.
If you don't have a schrader valve.... well.... that makes things harder.
If it were me..... I would remove the fuel rail and drop the injectors into four pop bottles and crank the engine
This way you can see the flow of gasoline.... it doesn't help you to know the fuel pressure.... but it will definitly confirm if your getting fuel into the cylinders.
If you have fuel and spark and the engine still won't start then I'm affraid your problems may be much more serious.... you may have a damaged cylinder head.
I guess one other thing is air...... you should ensure that when you depress the acclerator pedal that the butterfly valve in the throttle body opens up.
Anyways...... this should be simple enough for a back yard mechanic kind of guy to do..... I hope this helps a bit.