Is this a cat problem?
Every time I start the 98 bonny sse things seem normal for the first minute, then the engine starts bogging and rpm'* vary from 400 ish to 1100, back and forth. By the time I'm out of the driveway the pedal acts like it isn't talking to the engine. The check engine light has come on twice. Both times it says 2 codes dealing with bank 1 below threshold or efficiency low blah blah. I believe it'* code 0143 and some other one pointing to either the O2 sensor or the converter. The CEL doens't come on when the problems show up, but weeks later, then I have it checked and reset. My converter doesn't rattle and I have replaced both front and rear O2 sensors but nothing has changed. It seems like a TPS going bad or the coolant temp sensor since I notice most of the problem a few minutes after I start the car, but I noticed that even after the car is warm (200*) and is started again that the problems come back then go away after a few minutes of driving. Is this indicative of a cat converter going bad? Plus, don't those other sensors have their own code when they go bad? - I thought so. In the past when a converter went bad I could feel a definite blockage in the exhaust and power loss, plus noisy rattling; but such is not the case with this car. Like I said before, the DTC'* point me towards the cat, but I don't want to accept that. Isn't there something that I can plug in to the O2 sensor plug that tells the computer an optimal reading and makes the engine run that mixture all the time? Any help is appreciated.