i have a 03 chevy 2500hd with the 6.0. my check engine light will come on and flash. it does it between 2000 and 2500 rpms. It has a fresh tune up, 171,000 miles.

 

That is random misfire. Did it do this before the tune up?

 

yes the code was there before. this was the reason why i did the tune up wasnt sure when the last time it was done. it doesnt see to run rough or anything and it seems to happen more when its cold.

 

What all was done in the tune up?

 

Plugs and air filter the wires still looked good

 

They can look good, but can be deceiving at the same time, also check out the mass air flow sensor and o2 sensors and cats. All can cause the po300. If its flashin it's detecting a very bad misfire

 

What does it idle rpm, when cold? Do you have it after warmed up?

 

[QUOTE=kevinkpk;241060]What does it idle rpm, when cold? Do you have it after warmed up?[/QUOTE
Im not sure on the rpms at idle when cold. It doesn't seem to flash when warmed up. If the engine light disnt flash i would not know there was a problem