Truck sat over a weekend. Went to start idle momentarily then died. Then it wouldnt idle, had to give it throttle to keep from stalling. Next day worse, didnt wanna start then it sounded like a backfire when it did.
I checked fuel pressure, lines and oil leaks and it was all good.

 

Have you put a ODBII reader on it to see if it's throwing a code?

As to possible causes, bad gas, mass air flow sensor, throttle body position sensor would be possible candidates. Cam position sensor might be a possibility as well, but not positive on that.