So I replaced the rocker and pushrod on the bad cylinder... they work fine, but the valve is sticking. I get an occasional backfire here and there, and it runs rough.

I removed the valve cover again and sprayed the spring down with some diesel fuel conditioner in hopes it would penetrate through to the valve itself. I also used some wd-40 and PB Blaster.

Any other ideas, short of getting one of those motor-vac services done?

 

The valve could be slightly bent not allowing it to run through the motions

Have you overheated you truck lately?

 

No I haven't... but the motor is so gummed up I think the original owner was lacking an oil change or 2.... or ten haha.

Anyway... the wd 40 and PB Blaster/ fuel conditioner WORKED!!! I have triple the power in this truck now!! It runs so smoothly, accelerates like a bat out of hell, and I even had the truck sideways in second gear tonight!