I have been having very similar problems and have seen this issue all over the forums. After lurking around a lot, this is probably one of my first posts, sorry. I've tryed alot of the things everyone has suggested. Replaced coolant temp sensor, tps replaced and set it and isc. replaced oxygen sensor, cuz i was getting that code, replaced vac advance, thats what most people where saying would cause this issue. spark plugs are good, gaped properly. Has new plug wires, cap and rotor. going to the junkyard this weekend to try and find a maf, or the one from an eclipse, cuz i'm getting that code as well. I also had the same thing happen where it will throw the code for maf or o2 sensor, then go 12 volts steady, turn car on and off and back to normal, then throws codes again.
I've been fighting this issue for a couple months with still no problem solved. It does get better when the car warms up. and once I start to boost past about 5-7 psi it clears up and goes like mad. But issue is still there. And seems to come and go. Thought maybe it was fpr or maf, so will try those this weekend and let you know if I find anything. I've got 2 other friends who are mechanics and are just as baffled as me and everyone else. Hope we can figure this out soon.