hey everybody i did a search on the forum but i couldnt find much. i have a 98 ram with the 5.9 automatic 2wd with about 142000 miles. this issue started this winter and has been going on since. i always warm up my truck before i drive and the truck only sees shell vpower in the tank. basically about 2 minutes after starting my truck(with key or auto start-no difference) the truck starts to misfire and stall and smells like its running rich but with a little bit of a weird smell i cant really describe. most of the time it dies out within 45 seconds unless i press the gas pedal and hold at 1500 rpms. if i give it gas it still seems to misfire a little and if i hold the pedal steady there the idle clears up and gets to about 2000 rpms. if i let it die out and restart it the truck will idle fine. it occurs after cold start or sitting shut off for more than 10-15 minutes. the one idea i saw was saying the upstream o2 sensor and people recommend to disconnect it and see if it runs normal. any thoughts? and along those lines about 2 weeks ago the cel came on with that o2 sensor code the morning after i cleaned the throttle body. after getting it scanned and going home the next time i got in the truck the cel was off so i rescanned it with no codes.any help would be greatly appreciated. i should also mention the plenum upgrade was done and all normal maintenance has been kept up on.

 

Similar thing would happen to me about 3 months ago...it was the upstream 02 sensor. Replace that and you'll be golden...if you want to be sure, just unplug it from its harness on top of the transmission...it's a bit of a pain to get to but you should be able to reach it lying on your back under the truck. Unplugging it will make the truck run rich, but the idling issue should go away. Replace it with an ntk or denso or something...stay away from bosch.