Alright, I have been searching high and low for an answer to my truck's idle problem, and every single time I find a thread relating to a rough idle, their problems go farther than mine. As the title says, I have a 5.9 Magnum with only 85,000 miles, the truck has lots of power, sounds great, no engine codes to be seen, and doesn't use up oil (I am also using Mobil 1 Full Synthetic). Now to my dilemma, every time my engine gets cold, and by cold I mean when I let it sit there without running for a few hours, I start it up and runs fine for about 2-3 minutes. Suddenly, it goes into a rough idle, as if it has a lopey cam, and gets way below the standard idle RPM (I also can't tell the EXACT RPM because I have the Instrument Cluster without the Tachometer). Here comes the difference between my problem and everyone else's, when I start to drive away, it returns back to normal. It doesn't die or go back to a rough idle when I stop, I sat at Taco Bell in park for a good 45 minutes with no problems. But when it sits for 2 hours, and start it back up it does the rough idle.
I already cleaned the Throttle Body and got a brand new Idle Air Control Valve, any advice on what I should do next?
And it does have a hissing noise from the engine when it does the rough idle, and that's the only time it hisses or acts weird. I didn't check to see if I had a Plenum leak, but it doesn't use oil so I don't think that's an issue?
Any help is greatly appreciated
I already cleaned the Throttle Body and got a brand new Idle Air Control Valve, any advice on what I should do next?
And it does have a hissing noise from the engine when it does the rough idle, and that's the only time it hisses or acts weird. I didn't check to see if I had a Plenum leak, but it doesn't use oil so I don't think that's an issue?
Any help is greatly appreciated