2008 Grand Prix CEL Flashing

[Adam77]

I'm new to this forum and I am having a hell of a time.

To start, I have a 2008 Grand Prix, with a 3.8L V6 No mods.

About a month ago, the car died on the side of the road. Had it towed to the mechanic, I was told it needed a Crankshaft Position sensor for about $400. The next day the mechanic called me and told me it needed an ICM and #1 and 5 coil. New total was $800. I picked up the car and the next day the CEL came on and started flashing. Brought it back in and they replaced the 1 and 5 coil, and changed the #1 spark plug (code was reading P0301). The CEL still kept flashing.

I have now replaced all plugs and wires (no platinums, just copper plugs). I have cleaned the MAF sensors, and seafoamed the oil and gas. The CEL is still flashing and I am getting P0300 (random misfires).

I must add that in april I had replaced the mass air flow sensor for emissions test. then it passed.

The CEL only flashes when the engine warms up and at about 80 km/hr.

Can anyone help me out? I'm getting frustrated.

Thanks

Adam

[BillBoost37]

Based on what you've done, first off your mechanic took for your a ride, secondly..I wonder if the catalytic is clogged.

[Adam77]

Well he did fix the fact that it wouldn't start.

Last night I took it for a good boot, and checked the cat, it wasn't glowing. I don't know how else to check.

I looked at the throttle body and it's really dirty. Gonna go out now and get some cleaner.

[stocker]

I believe you are supposed to be using IRIDIUM plugs not copper.

[Fivefingerdeathpunch]

Copper is fine, they just last 1/5th the time. Change every 10-15k atleast.