Ok I am in need of some advice here...I have a 2000 Suburban with a 5.3. It runs great off of idle, but when idling it has a slight irritating random miss. The truck had a code for the Catalytic Efficiancy so I put 2 new CATS on it and the code has not been back since, but the miss still lingers. I have also put a new fuel pressure regulator, fuel filter, fuel pump, PCV, and cleaned out the throttle body. The truck needed a fuel pump anyway - the old one was SCREAMING and the gas guage would occasionally drop to "E". So that wasn't a total waist, but nonetheless I am appoaching $1000 of repairs and that little miss still haunts me! HELP!!!!!
P.S. There aren't any current DTC's.

 

Plugs & wires possibly. Have you had your battery & alternator tested lately? Could be a vacuum leak too on a hose.

 

I have not had the battery or alternator checked, but the truck starts fine and the guage is just under 14. I have traced all the vacuum lines that I can see and don't see or should I say hear a leak. Is it possible to have a bad sensor without the computer picking up on it?

 

I did pull one plug and it was very white (lean looking).

 

Got me stumped, my next guess would be in the fuel/exaust system someware( bad sensors etc..), or even a gasket possibly.

 

OK here is the latest...today I put new plugs and wires, removed and completely cleaned the throttle body, removed and cleaned the EGR valve, and cleaned the IAC valve while the throttle body was off. I let it idle for about 15 minutes and it sounded good. I am a little concerned b/c the old plugs were extremely white (lean). They all looked the same though. I am going to test drive it tomorrow. Wish me luck!

 

Well I think I may have fixed it. I drove it today for about an hour (round trip) and it never missed. So something I did yesterday must have helped. I hope it was the plugs and wires so I can justify the $70 I spent on them. Everything else was basically just labor. It actually feels like it accelerates a little smoother as well. Not that anyone but Mike has replied...thanks for all the help guys!

 

Plugs were probably the answer. Mine stumbled a lot a week after I bought it but new plugs cleaned that right up. I didn't do the wires/cap/rotor yet but haven't seen a need for it yet.

Glad you got it solved!

 

Glad you got er running better, I am always up for a brainstorm. I have a feeling everything you did played a part in the better performance.