so i was listening to my car idle and it seems to be missing every 2 seconds. I brought the idle upto 1500rpms and sure enough its missing on one cylinder I suspect.
I had a similar problem on my 99gt. Check this:
water or coolant around spark plugs. Remember NEVER wash down the engine
I had coolant coming out of the intake manifold gasket. Just barley, not enough to drip on the ground, but enough to make moisture in 2 plug holes.
if you EVER had water in a plug hole, you probably killed a coil or 2.
You can narrow your problem by doing the following. This will tell you where the problem is, and if it is spark, or fuel related.
1. Get your car in a state where it is misfiring. It must be misfiring for this test.
2. one at a time, unplug fuel injectors while the motor is idle. The engine should have a noticable lope when you pull each injector. This is GOOD. It means the fuel injector is working. If you get to an injector that DOESN'T cause the engine to lope when disconnected, or causes it to lope less than the others, suspect that cylinder. Do this 2 times each for each cylinder to see if you get the same results. Most likely, this is not a fuel problem.
3. Rev the engine a few times and then let it idle for a minute and make sure it is still misfiring.
4. assure that all injectors are connected properly
5. One at a time, go around and disconnect the plugs from the coils. Again, doing this should cause a noticable lope. If you get to a coil that when it is disconnected, it either doesnt lope, or causes less of a lope that the other cylinders, suspect that cylinder.
Ok, so hopfully now you have narrowed you problem to a specific cylinder(s) For this write-up's sake lets say cylinder #5 is your problem, but your still unsure if it is the coil or injector because during both tests, the engine still loped, just not as much as the other cylinders.
6. swap cylinder #5 coil with a coil from the other side of the engine. (You will need a small 7mm socket and extension to remove the bolt holding the coil down. And the coils will come out without removing the fuel rail.)
7. connect both coils to the wire harness and start the car. It should still misfire. Use the method in step #5 of this write up to see if your misfire followed the coil, or is still happening at cylinder #5.
(If the misfire followed the coil, you have a bad coil. whats worse, is the others are probably on their way out too. Replace them all.)
If the problem stays at cylinder #5, then suspect your injector.
8. Use compressed air to blow dirt off the motor before doing the folowing procedure!!
9. Using a 5/16'' wrench or deep well socket, remove the 2 nust holding both fuel rails down.
10. Remove the intake plumbing. PITA i know, but it is well worth it.
11. Lift gently and evenly on the fuel rail until all 4 injectors are clear of the manifold. It is a Bioch to pull, so just go slow and steady. Repeat on other rail.
(there is no need to releave the fuel pressure, you will still spill fuel, just let it drain on the motor, it will evaporate in a minute)
(And, duh... I know most people don't work on their engine after cruising the interstate for hours, but if you do, please do this when the engine is sorta cool so you don't blow up.)
12. Visually inspect the injector, don't clean it yet even if it is dirty or looks clogged.
13. Switch it with an injector from the other side of the engine.
14. re-install everything and start it up. See if the misfire followed the injector. IF it did, clean or replace the injector. If the misfire is STILL at cylinder #5, then your only possible causes left are:
1. The sparkplug (you said you checked these already)
2. mechanical problem within cylinder #5
3. the connector or wiring to cylinder #5's injector or coil
Hope this helped. IF you follow this without cutting corners, you WILL find your misfire.
Note that a multiple cylinder misfire should be aproched using this same method, just make sure when you go to swap coils and injectors, you are swaping with known working cylinders.