1998 Random cylinder misfires and code P0420 - GM Forum - Buick, Cadillac, Olds, GMC & Pontiac chat

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1998 Random cylinder misfires and code P0420


Old 10-07-2008, 12:41 PM
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Default 1998 Random cylinder misfires and code P0420

Hello everyone, new here, but thought I would try to make a post and see if I can get some help with this because its really starting to annoy me that I cannot figure out what is wrong. Have a 1998 Pontiac Bonneville that the check engine light first started coming on. Got the code and it was P0300 and saying that cylinder 3 was misfiring. So from that, replaced all 3 coil packs with new coil packs, changed spark plugs and wires and it seemed to be running better. Ran ok for a while but then the code came back and the transmission wasn't wanting to shift properly. so I took a whole sunday to replace the Transmission filter and gasket. put a fuel filter on, oil filter and oil, and still was running really bad. Pulled off cylinder number 1'* spark plug wire and it broke, so we went and got new wires, put them on and it seems as if now it hesitates more and more than what it did before. now when you start it up at idle it first chugs really bad and then slowly the idle evens out like its not getting enough gas to hardly even start the car, let alone accelerate and go, any suggestions????
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