Truck exhaust sputters at idle, only when the engine is warmed up and operating at normal temp. I am guessing something with the AFM - the engine has new plugs, air filter and a clean throttle body.

http://s53.photobucket.com/albums/g7...P1000508-1.flv

 

Grab a timing light and see if the timing is bouncing around (jumper the diagnostic plug as if you were going to set the timing too). If it is, your timing chain may be stretched too far for the tensioner to take up the slack.

 

thanks abecedarian, I will check the timing chain. If it is streched does that mean it needs to be replaced, or can it be tightened with the tensioner? I know the replacement is a pretty lengthy process.

 

The tensioner might also be broken

 

I guess I have a question, if it is the timing chain, why does this happen only when the truck is fully warmed up?

 

Metals act differently when heated

Its hard to say for sure but i had a similar noise and it was fixed by a valve adjustment

good luck

 

stick a dollar bill in front of the exhaust.. does it ever get sucked back briefly? If so... a valve is sticking

 

Ok, so I tried this and the paper was indeed getting sucked back in to the exhaust briefly each time the exhaust "coughed" So this means a sticky valve?

Is there a way to lubricate this with seafoam/etc in the crankcase or vaccum system or is it clearance issue?

Could it be anything besides the sticky valve, a timing issue possibly as abecedarian suggested?

The truck runs great under acceleration or at anything above idle. Why is this only happening at idle?

 

about the only way there can be any suction at the tailpipe, is if an exhaust valve is not fully closing, or exhaust valves... so yes...it could be timing, but I'd think it would run pretty terrible if all 6 cyl's were sucking exhaust.

Seafoam may help... Adding some atf to your crank could help if its a sticking valve.... if its a burn velve, or a valve('s) out of adjustment tho... it will need to be fixed right.

I would start with a compression test, then decide where to go from there.

 

Just a thought in a different direction my truck with the 22re sounded just like that and since you said the throttle body is cleaned I'm assuming you cleaned it recently? If that assumption is correct then your problem might be similar to the one i had last week. I recently cleaned my throttle body and didn't remove the tps, stupid but i had no clue at the time. Shortly after i cleaned the TB my truck idled just like yours and sputtered and spit throughout the rpm range. This is on a newer motor and i couldn't for the life of me figure it out. Turned out that the tps was malfunctioning and when replaced solved my problem. Check out 4crawler's page on testing the tps it might shed some light on your situation and its free to just check something like the tps all you need is a ohmeter.