Vehicle Problem :
I have a 2002 Pontiac Grand Am and I changed plugs, wires, coilpacks , egr valve, fuel filter,oil&filter,air fiter miss fire was determand from my code finder i am stumpt here
Already Tried: plugs,wires,EGR,fuel filter,oil change
I have seen this several times and it is caused by the catalytic converter being clogged. To prove this is the issue, take a back pressure reading at the front O2 sensors. It should be 1.5 psi or less. Anymore than that and it will cause this issue.