[s-cars] Hesitation -- please help

[Adam Cramer]

All-knowing S-car list,
 Please, please help me figure out what is causing my hesitation issues. 
 I finally got around to testing my coils tonight. I thought this would 
solve my hesitation (under load) issues, but all 5 of my coils seem to be 
fine. I used the adjustable spark gap tester and each of the coils made a 
nice clean, crisp, blue spark about 3/4 - 1 inch long. I couldn't find a 
weak one among them. I really tried to tell myself that the #3 coil was bad, 
but everytime that I would re-test it, the spark would come back nice and 
crisp. ARGH!
 Symptoms include hesitation under load, especially in the higher gears (4th 
and 5th), although occasionally I will feel the problem in 2nd and 3rd. It's 
not violent jerking like the fuel is being cutoff, but more of just a 
hesitation and general lack of consistent, smooth power to redline. 

Here's a list of stuff that I have fixed/checked/replaced so far:

5 new Spark Plugs (Bosch OEM)
2 new POS units
New Fuel Filter (OEM)
New Air Filter (OEM)
Checked for air leaks
Checked for weak coils
Checked plug boots (good condition)

Anyone have any other ideas, either electrical or fuel related? I think I've 
tested all of the electrical options. What about the alternator? Any chance 
a weak alternator would be causing this? I did have an oil leak a few months 
ago that caused oil to accumulate on the alternator. 
 More background on the car (if it helps you diagnose the problem)......RS2 
turbo, em, maf and injectors. IA chip. Forge BPV (yellow spring). Another 
issue with this car that I haven't been able to solve is that the idle RPMs 
fluctuate when warm. Usually between 800-1000. I doubt this is related to 
the hesitation issue, but I thought I would throw it out there just in case.
 Any help is appreciated.
 Thanks,
Adam

This is definitely a love/hate relationship.