no codes on the computer at all, it sounds like a slight misfire from the moment I start the car. there is no change between open and closed loop. It is most noticeable when accelerating, it smells a little rich and has no power when accelerating. I can drive the speed limit it just gets there slower than my old 4 cylinder ford ranger. when I hit the gas hard it bogs down then will accelerate but not at all like it always has. It had a few things go wrong at the same time, the fuel pump was weak so I replaced it and there was a plug wire that was bad and arcing so I put new plug wires in and plugs but that just made things better by a little bit. I have been trying to figure this out for almost 3 years so it has been very frustrating. I have the obd1 cord for pc so I have data logged many times and things show up good except the fuel trims are a little off like it thinks its a little lean so its adding extra fuel that it doesn't need. The o2 sensors are cycling good and as far as I can tell the sensors are all reading like they should, maf, map, iat, tps all reading good. I have replaced the maf a while ago because it fit the symptom's but my old one worked fine so I have an extra, same with the coil. The only thing I can think of it being is the opti but that is a gm unit that only has a few thousand miles on it so I don't want to put all that time and money in until I know more so its not just a guess. It also starts right up weather its a cold start or its warmed up but I can hear the "misfire" right away. If I wasn't as familiar with the car I probably would only notice the problem when accelerating but I have owned the car over 10 years so I know how it should sound and feel, I am probably missing something because I have tried a lot to fix it with no luck. If you have any suggestions please let me know because I miss my car, thanks for the help.