So...just my luck.

The car is a 2003 supercharged ecotec.

Last week my car decided to give me a p0300 code. No noticeable misfire or hesitation. It seems to set the code when im traveling at a constant rpm around 2500-3000 and when it sets the code I don't notice anything out of the norm.

I clear the code and it may go a week or a few days to set the code again.

I dont hear any difference in the idle or notice any difference in how it runs. Seems as smooth as it always has.

I went for a 1000 km drive this weekend and it drove just fine, but on the way home I got a p0304 code a couple times. each time I deleted it.

I decided to check on my interceptor and according to it im getting quite a bit of misfire, and its very random.

I pulled the plugs when I got home and they all look good and tan, so no noticeable cylinder that's doing badly. I changed coilpacks since I had a spare and it seems to not have changed whats going on according to my interceptor.

Im kinda not sure how to attack this.

I am wondering if a bad alternator could be the cause of this since its a new issue and it seems like one of the bearings in my alt is going. At idle im getting around 13v, and with higher rpms im getting 13.5 or so. Seems low to me.

IAfter reading around the net it seems it could also be a bad fuel pump or pressure regulator. Im going to get the stuff to put a gauge on my schreader valve so I can monitor the pressure.