My 2000 Chevy Blazer keeps throwing the P0300 muliple/random misfire code. Im stuck on where to go now. I have replaced plugs, wires, cap, rotor, fuel filter, air filter, spider injector and I removed my cat and installed a pipe. Any help would be greatly appreciated. Thanks

 

Then.. I assume enough to lite SES and you have no other codes pending.
- I saw last night while checking something else I have P0300 pending. I know why.. needs tuneup.

- Sorry to inform you that means nothing unless you used ACDelco or NGK products specified.
When does light come on, in particular? at steady speed/ cruise? While idling?

If you used Bosch Plats.. start there. If you used Autozone budget wires/cap/rotor.. replace those as well.

Do you have starting problems when raining or damp overnight?
Run engine in dark, look for arc-over.
- cant hurt to clean the coil tower and lube it and wire with silicone lube or spray.

Check cap inside and rotor for signs of wear and friction rubbing deposits, etc.

While there wiggle rotor.. any signs of slop?
See next post..
Know anyone with a timing light?

Hook to #1 and look at the crank pulley with engine idling relatively smooth, any identifying marks on pulley will do.. do they jitter or dance? Distributor slop!

 

My 2003 S10 Blazer did the same thing until one day it would not start I found I had a bad distributor. Replaced it and have had no problems since and runs better than it had in about a year