i have a saturn L200 with dtc p0300. runs great down the road has recently developed a slight miss at idle . i have swapped out with a known good coil pack no change still has the miss ,have also cleaned throttle bore and plate.Have also checked iac valve and moves in and out when i turn key over so i assume its good any suggestions r greatly appreciated . thank u .

 

Get off somewhere on a dark night (no lights). Start the engine up, and look for sparkplug or associated wiring shorting out

 

i forgot to mention i have a 2.2 ecotech i have no plug wires.

 

Inspect the plugs and caps.