Anybody have trouble with a 2004 supercharged grand prix with a misfire in cylinder 3 and 4. Especially under heavy load with pedal 3/4 to all the way down.
Check engine light is blinking. Both spark plugs showing misfire.
The catalytic converter does need to be replaced.
Compression is good.
You can tell a little rough miss during idle but no codes during idle.
Anybody have this trouble before?