Ours was simple... as in 95% of ALL car problems. Usually just hard to determine what 'exactly' is wrong in the first place. New plugs made ours run 1000% better. Wires didn't help, but if you're replacing plugs, especially 'old' plugs, do the wires too. Check and clean the cap and rotor if any. The final problem was to get a new Cat. Converter and weld it on. (Light was coming on intermittently) Dokter Denney
Carb.? Float sticking and flooding
Poor maintenance and/or bad ignition coil.
Morgan
I have a 2004 gt that has also developed a rough idle also and can't find the problem.... I wish you had the answer....
my 1990 300zx is idling rough what could cause this?
Why does my 2001 kia sportage idle rough?
why does my vr commodore idle rough when at complete stop
rough idle smell gas
the radiotor or the cams
When the idle goes rough, you must idle the plugs. Else the car plugs roughly.
With mine, the rough idle was fixed by changing the spark plug wires.
A Grand Prix can idle rough for many reasons. The timing may be off, the fuel filter may be clogged, or it may need a tune up.