RE: returning check engine light
 

No offense Argon, but it says Single/Mutiple cylinder mis-fire and my truck does it all the time due to theO2sensor readings I get from removing my cats.

RE: returning check engine light
 

well,if all 4 sensors are gone,who knows wtf...but 1 03 sensor being lazy or skewed should not set a 300..

if your repeatedly setting a 300,it must get some awful mpg

RE: returning check engine light
 

its bin good this week. fuel filter only has like 15000 on it just like the plugs.

RE: returning check engine light
 

If it only does it when it's cold then it's probably intake gaskets leaking. Try this: when you start it cold, take some brake clean and spray around the intake and see if the idle changes. if it does, then your intake gaskets are leaking. If its a 5.3, that's a common problem. GM has updated gaskets for them. I've replaced alot of them (I'm a tech at a GM dealer). They'll run you about $100. They're not too bad to replace. Also, if you're running aftermarket spark plugs, put AC Delco in it. Fixed alot of misfires by replacing aftermarket pulgs with Delco.