My car idles ok and revs without any load. Its fine at low rpm when driving but seems to miss badly in the 1500-3000rpm range and cleans up a bit after that. It will literally cutout for a second and then pick right back up.

So far I have
Tested the IAC, IAT and ECT for resistance and voltage coming in.
I checked for flashing pulse at the injectors.
Checked for spark at the coil.
Checked for spark at the plugs(copperish spark with plug on manifold).
I checked compression fairly recently and it was pretty even across the cylinders.

There is no engine light.

Any more tests I could perform to narrow it down further? I tend to jump to conclusions instead of being logical when it comes to my own car.

 

You might get better responses if you told us things like what year it is, how many miles on it. What's been replaced either through troubleshooting or just routine tune ups.

Have you ever looked under the hood when it was dark out to see if any wires are arcing?

 

93 z28 m6. Car has 220,000 kilometers on it.
I replaced the optical part of the distributor less then a year ago.
Wires/ plugs are a few months old.
I have an extra coil that I have swapped with the same result.
Coolant temp sensor in the water pump is new.
Timing chain is about a year old.
Head gaskets are also less than a year old.

The car had a mid rpm miss before I let it sit for winter, it is now considerably worse than it was. thanks

 

What about clogged/dirty fuel injectors? Take them out and clean with a que tip and some carb cleaner. Did wonders for mine...

 

Hmm, could be the injectors I guess. I may give that a try if all else fails.

I started the car and noticed it puffs sort of a greyish smoke after it has been running for a minute(only seems to happen at idle).

Also the exhaust is popping and snapping every 1 or 2 seconds, I assume this must be a symptom of a few problems.

The car has real duals and smokes equally out each pipe, however the popping/ snapping only seems to come from one side of the exhaust. Anyone have some suggestions

 

Check your fuel pressure. I have a the same problem and it was a bad fuel pump. You should get 35-40 psi by just turning the key forward. if the fule pressure is ok, Replace the cap and rotor. These part do wear out faster than the opti itself.

 

You might have a different problem than me. My clogged injectors were causing the engine to compensate by running rich so I was getting a little black smoke. It drove me nuts for months until I figured it out using DataMaster. Just a thought.

 

Fuel pressure I hadn't really thought of that but I guess it could causing my issues. I will have to get ahold of a pressure guage(mine "disappeared"). Seems a little unlikely that it would be so consistant.

Anyone else have any ideas what could cause this?