Thread: Having problem chasing down Random misfire

I have a 2002 Pontiac Gran Prix GT with 144,000 miles.Just replaced cat and coil pack and maf and also drive belt.Had Advance check batt and alternator ok.Check engine light flashing then goes solid when at stop or idle.Spent a lot so far and need answers before I break the bank.Can someone help me? Thanks

Code is po0300 and changed wires and plugs last summer

Originally Posted by BillBoost37

What did you change the plugs/wires with for replacements. Brand name and or model on the plugs please.

It was done by Goodyear shop and looks like plugs are ac deco and wires look ok as I pulled off to check and pulled plugs and they were not fouled, they looked good to me

I don't know and I didn't ask as I was in Goodyear for tires and asked to have tune up, I do know that plugs are AC Delco because I pulled them to check

The car started acting funny weeks ago like bad hesitation and miss especially on up hill. I thought bad gas and added fuel system cleaner after replacing fuel filter. Progressively worse as loss of power to point of just putt putting along. Will make it up to speed limit but when slow down to stop it wants to die but give it gas and ok. It will idle at times ok but then you feel miss and shakes car. Other things done in last six months is replace water pump because overheating issue and thermostat replace too.Just put on at a garage a Walker cat that was a exact fit replacement. Mechanic said needed MAF too so I did. Replace coil too no better. I am now officially a bonafied nut case .... This really sucks

Oh yeah check engine still on but now flashing at speed but stops and just stays lit at stop