Here goes had my plenum gasket replaced under what was left of my warranty and after i got it back the idle has been rough around 650rpm. Originally i had a check engine light, but after checking plug wires 5&7 found they were reversed. switched them and havent had a code or light since.. but the idle is still rough. any help.........2000 2500 4x4 97500 miles 360ci

wires are new and plugs are new.

 

try replacing the distributer cap and rotor.

 

there both less than a year old...

 

did the dealer do the work? maybe they messed somthing up on the tb
have u checked all of your vacuum hoses?

 

You had the plenum fixed under warranty and then you get it back and the wires were crossed. What dealer was this? Thats f---ed up

 

Try running some cleaner through it; like Sea Foam.

 

Sounds to me like the Evap Purge Solenoid tubing was connected backwards. I had this happen when I rebuilt my engine. There is a hard line out the front of the throttle body that winds around the passenger head to the driver's side rear of the engine. The is another tube coming of the Purge Solenoid that goes down to the charcoal evap canister, located under the driver's door. If the two lines are backwards, the idle will be off. Swap them and I bet your idle returns to normal.

 

start the truck. take a long screwdriver and place it against each of the injectors and listen to the handle. each injector should make a continuous clicking sound. the screwdriver works like a stethescope. i bet that maybe an injector might be screwed up.