1990 Chevy Corvette Lean Burn Miss

The first thing I would have changed would have been the oxygen sensor. Did you forget to mention that, or are you saying that three different shops overlooked that?

Good Luck.
Dr. Loot's Assistant

O2 sensor was replaced sorry I forgot to list that.

Compression is good accross all cylinders and there are not any computer codes coming up.

Well, with all that you have listed, I'd expect that the problem would have been solved. So, we have to conclude that it's something we haven't thought of, or that some of the parts you paid to have changed weren't properly changed, if at all. But, assuming that they were, at this point, I would go to the shotgun approach. We need more data. Here are some ideas (and, at this point, I'm stumped so I'm shooting in the dark hoping to stumble across something):

1) try boosting your octane to a 100 or more with some of the available fuel additives. See if that makes a difference.

2) get an emissions test station to verify that your car is actually running lean at idle.

3)try pulling a spark plug wire and connecting it to a grounded plug external. Do that for each cylinder. If the miss is entirely located in one cylinder, you may be able to hear the difference.

4) on the possibility that your injectors weren't really changed, get a stethoscope and listen to each one. Maybe you can detect a difference.

5) spray starting fluid (carefully, have a fire extinguisher on hand) around the intake manifold and listen for a change in the engine idle. This can help locate a vacuum leak.

6) run some BG44K through your fuel system. If you have an injector that is not properly misting the fuel, this could help it.

7) do a leak down test to determine the health of your intake valves

That's all I can think of at the moment...

Good Luck
Dr. Loot's Assistant