04 chevy k1500 4.9L 146k miles. got truck about 3 months ago and always ran good no problems. washed truck in wash rack at work and let sit 2 hrs and dry off. went to start it and leave started and stalled. ok its just wet... never done that before. ran bad , stalling and skipping down road even 2 days later. has new tune up and good wires and plugs. put dry gas in and injector cleaner. thought might have been bad gas . still stalls idles really low like 400 or 500 rpm and stalls out at stop lights or slowing down. checked it and has no codes . please help

 

Check you throttle body for carbon build-up. They should be cleaned periodically or they will cause your exact symptoms. Use throttle body cleaner and a rag (a toothbrush works well if it is really bad). Also if you want to be real thorough remove the throttle body and clean both sides. I think you meant 4.8 liter right?

 

Sounds kinda like your catylytic converter is busted up and is clogging your exhaust. Cut that rattle trap out and weld in some pipe!!

 

If the underside of the truck got washed, the water coulda hit the cat with enough force to booger the inside of it up. That would explain why it started actin a fool after gettin it washed