[tblake]

I had a 1990 lumina 2.5L 4 banger with 190,000 before we got rid of it, and one night at 11pm, coming home from work, just all of a sudden looses power, and eventually dies. I pulled over, started her right back up, and revved it a few times, all was well, revved up, and idled great, till I put a load on it (put it in drive) I could only get my speed up to about 20-30mph, and eventually it would stall again, I drove it home this way, only to pull a code that said a faulty O2 signal. I replaced the O2 sensor, and all was well. Try that. Its in the eshaust manifold right near the front of the engine, or at least mine was, and it has a single wire coming from it. First check to make sure this wire is in good shape, and isnt in contact with anything hot, that can melt the coating, and cause a short. Good luck with everything. Oh, ya, and PS. I doubt very much that tapping on an O2 sensor would cause an engine to run bad, even if the O2 itself was bad. Although this method does work on many sensors.