rough idle. backfiring, loss of power

[fastamp;furious]

I have a 1994 lumina euro, 3.1. Got it 2 weeks ago. When i got it it had no fuel pressure. replaced fuel pump. That problem solved. but when it started it idled pretty rough. when i accelerated it was backfiring thruogh the exhaust. the harder i acelrerated the harger it back fired. when it warms up you lose power. the cat rattles and glows red when the engine warms up. I pulled codes and all i get is the 12 ( handshake code). I replaced plugs yesterday. Three of them looked good, one had the electrode burnt off, one the internal insulator was busted,and the other looked a little black. when i got done the idle had smothed out quite a bit but still a little miss. The backfiring cleared up alot but still some faint popping. I know i need to do something about the cat. any ideas about the remaining miis and slight popping in the exhaust??? one other thing that may ormaynot be related- when you take ff and its time to shift (4t60e ) it wont shift unles you let off the gas a little( it does not slip). Sorry for the long post i just wanted to get all the facts out there to make it easier on you all to help. thanx

[Supreme Cutlass]

You have a clogged cat., so getting that taken care of might help. You might try a new O2 sensor, some slick 50 fuel system cleaner too, with a new fuel filter.

[ShockTherapy]

You have a clogged cat., so getting that taken care of might help. You might try a new O2 sensor, some slick 50 fuel system cleaner too, with a new fuel filter.

 

what he said, minus the slick 50. that shit'll fuck up your engine.

[Supreme Cutlass]

You have a clogged cat., so getting that taken care of might help. You might try a new O2 sensor, some slick 50 fuel system cleaner too, with a new fuel filter.

 

what he said, minus the slick 50. that shit'll fuck up your engine.

 

If it's as clogged as it sounds, slick 50 fuel system cleaner will help... it sure did with mine.

[gp90se]

berrymans fuel injector cleaner is by far the strongest stuff on the market if you wanna clean the system out. cut the cat off for now, put in a piece of pipe and drive it around, see how it feels. when you do replace the cat, replace the o2 sensor as well, thats typically the reason cats fail.

[fastamp;furious]

Is berrymans fuel injector cleaner somthing i can get at autozone or advanced auto??? Also any ideas about the trnny shifting issue??

[gp90se]

autozone carrys it, $2.99 a bottle, its in a 16 oz white bottle iirc, follow the directions to a T.

 

with the cat off, see of your still having the tranny issues. My 90 grand prix fried the car, soon as I yanked it, the tranny shifted like it should again.