I have a 2001 1500 5.9l v8 4x4 190,000km. Lately it has developed a horrible idol and runs rough. I notice it more from a cold start but it does it randomly at all times. If I leave the truck to idol, it runs fine for about 2 minutes then the rpms become spurattic and it runs horrible almost as if it wasnt to die. Until i touch the gas and it jumps back to life for a second, then if i leave it, the same thing will start to happen. Once the truck is warmed up it can keep a constant idol not to bad. The other part of the issue is when im driving around town, the truck will suddenly start to slowdown, or feel powerless, the rpms start to flutter, it will kick and buck and hesitate, even with my foot on the gas. After a few seconds i will begin to hear a popping sound somewhere in the front of the truck as the truck runs horrible down the road. If i stomp on the pedal it usually clears up and runs normally. I notice it acts up when i shut the engine off and start it up. But if im on the highway driving for a few hours it only does it at the start of the trip and runs fine after it has acted up. Im clueless. Ive replaced the crank position sensor and the throttle position sensor. Could it be my o2 sensor? Anyways sorry for the long read, thanks in advance!

 

Also there is no check engine light, fluttering the gas pedal can usually get the engine out of its slump when its acting powerless.

 

Read the sticky titled "The be all end all plenum thread" at the top of the page. Will answer all your questions.

 

Try the (upstream, "pre-cat") oxygen sensor. Crawl under there, unplug the pigtail connector (usually found above the transmission, of all the fine places for it), and go for a ride. If the symptom doesn't occur, replace the sensor. I'd bet a dollar that it's the oxygen sensor causing your woes.

Also, as jkeaton recommends, check out that intake manifold plenum gasket. If it's leaking it'll cause all kinds of expensive problems that you don't want.

 

I dont know why i didnt think of it before. I unplugged the fuse to the o2 sensor and my truck seems to run great. The real test will be tomorrow morning when I start it cold. Why wouldnt my check engine light come after running with the fuse gone on the sensors (checked the bulb still works haha)

 

02 sensors may or may not give a CEL . I've always unplugged them for tests , and they always give a CEL . Maybe the fuse is different .

I'd bet on the 02 sensor also . NTK replacement recommended , Bosch is not .

 

Just an update, I took the entire intake off, cleaned up the throttle body, maf sensor, replaced gaskets and a couple of corroded vacuum lines, put back together and all is well. So I am going to assume it was a vacuum leak or clogged maf.

 

I think you posted in the wrong thread.... This one is 5 years old.