chasing codes 2000 Bonneville
i have been trying to figure out why my 2000 Bonneville is running so poorly. I have had several different codes, all have to do with misfire and running lean. Some of the symtoms are rough idle ( not always). Blinking SES light under acceleration and also not really accelerating, this smoothes out after acceleration stops. My wife had the car stop on the interstate with temp rising and warnings about disabeling the AC. first code was misfires so I changed plugs and wires and got good results for a short while, then got lean left bank, this is when the car stopped on my wife. Changed the O2 sensor and runs mush better but now code shows lean on right bank and misses that come and go for cyl 3, 2, 6,4, Mostly cyl 3. I thought maybe conveter is stopped up but why would that cause leans. Had smoke test run and found no vacuum or intake leaks, changed fuel filter and tested fuel pressure it is about 45psi it jumps around when engine is revved but never drops below 40 psi, cleaned Mass air sensor (fairly new one) still runs poorly. Do you think fuel pump or converter or is there some way to test for either. Coils checked good at garage.