Okay, just got off the phone with the mechanic. He's scratching his head, just like every other mechanic who has touched this car. I'm about the throw a temper tantrum.

He did extensive checks for vacuum leaks and he said he's willing to bet his life that there's no vacuum leak. Used a smoke machine and everything.

He tested the spark, and found that cylinder #4 is misfiring and that the signal is inconsistent. He swapped out the wires and still said that fixed the spark problem, but the car is misfiring all the same.

He seems baffled. He thinks it COULD be the fuel distributor, which was replaced not too long ago with a rebuilt unit... I think he said it was rebuilt by some outfit named viper or cobra or something like that... I should've written it down. But he said he's tried two of these units on the same car once before and they didn't perform well at all... and that he eventually went to a wrecking yard, picked up a rebuilt unit, and the car was smooth as silk... so maybe my rebuilt fuel distributor is effed.

I actually am really lucky, because he has another 1990 300ce in his shop right now. So he's going to swap out the EZL units just to test. But he is skeptical that it will be the source of the problem.

In general, he said he's having a tough time zeroing in on the problem because whenever he tinkers with one thing, it changes everything... that the problem is so inconsistent...

I'm nervous about what the repair bill is going to look like...