The plenum sounds like a good culprit. You may even have a valve that wants to stick. Have you ever tried to use an upper engine cleaner? Just a thought.
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I'm going to put in a vote for the oxygen sensor. Mine ran like crap--it stuttered and backfired frequently, often stalling right after leaving a stoplight. A new front O2 sensor cured the problem completely. The heating element was bad and when the sensor cooled off (like when idling), it stopped working.
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Matt Harwood
Cleveland, OH
1998 2500 SLT 4x4 Quad, long bed, 5.9L V8
www.harwoodperformance.bizland.com
Sometimes yes, sometimes no. Mine would come on, then go off by itself. It wasn't the O2 sensor that was bad in my case, it was the heating element, so the codes were rare. I wasn't able to get a definite answer that it was the heating element until I took it to the dealer and convinced them to scan it for me. The AutoZone guys often couldn't get a code out of it and if theMIL isn't on, they can't get anything. The dealer can checkhistory codes as well as current codes.
But I agree--if there's no light even once in a while and no codes, then it is probably the plenum. It's always the plenum.
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Matt Harwood
Cleveland, OH
1998 2500 SLT 4x4 Quad, long bed, 5.9L V8
www.harwoodperformance.bizland.com
You can try to use the gas tank cleaner but there are also others such as seafoam etc etc. tear that t/b off and take a look inside that will give you an answer real quick about the plenum. I am hopingthe plenum fix will cure my "what I believe to be transmission problem" thing I have going on.
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so if I take the throttle body off what am I looking for?
from the service manual 14-49 (page 1536 in the PDF) it shows that I have to take out 4 bolts and the sensor connectors for the MAP sensor, Idle Air Control Motor, and the Throttle Position sensor. I'm assuming after that I will have the throttle body in my hands? do I need to replace the gasket or can I reuse the one that is in there? also am I looking into the throttle body or down into the engine?
At that point your linkages will still be connected but you can set it off to the side. Get a flashlight and look down into the intake towards the back. You will be looking for pooling of oil. Hopefully not a lot if any. You can reuse the gasket unless you tear it up.
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I don't think its the plenum... I pulled the t/b and I did not see any pooling oil anywhere. I was unable to pick up a o2 sensor this week so I'll have to try replacing that next weekend.
RE: Backfiring issues.
