"orginally posted on www.truckforums.com" I am new to this forum thing and I don't know if this question has been asked already. I have recently received a 99 Ram 1500 with a 3.9 liter V6 and 5 speed. The truck was (to say the least) abused prior. When I got the truck the cat had been cut out and the back O2 sensor had been cut ahead of the connector. While driving, the first 15 minutes are fine, but after 15 minutes pulling up to a stop light is embrassing. The truck will cough, gag, spit and sputter unless I redline it and slip the clutch to get it going. Once moving it drives fine. And it doesn't do it at all stop lights. When it does do it you can hear massive amounts of air getting sucked in but the butterflys don't move. I've run a code reader on it myself and had a shop run a hand held diagnostic, but no codes. Only thing that seemed odd was that the reading from the back O2 sensor never changed (it was repaired from being cut by soldering the the new sensor to the wiring harness). I've also changed the front O2 sensor, Idle Control Motor, Cat Converter, cleaned the throttle body with intake cleaner spray. I've checked for vacuum leaks and for proper voltage at all the sensors. Does ANYONE have ANY IDEA what might be going on. I have no idea besides for changing the MAP and TPS and finally the computer. TPS isn't expensive but the MAP is $80 and the computer I can only guess. If anyone can help PLEASE post any suggestions. Thanks.

 

You've changed the IAC, but did you clean the TB before you changed it? Also of stuff can get in the TB and cause it to run crapy.

 

I removed and cleaned the complete throttle body. It was dirty but nothing that would have affected the IAC valve. Every once in a awhile I get a code to come up on the reader "O2 sensor has high voltage Bank #1, Sensor #1". I am taking it that this is the sensor before the cat. Which I've changed once. But doesn't come up all the time. I drove it to work today (15 miles) and it coughed and gaged 3 times but no codes came up. I did relize I forgot to say in the first post, when it does start acting up, if I "can" floor it, it accellrates great and clears up the idle for a few minutes. This makes me think its in the fuel delivery. I am ruling out a clogged filter or a bad pump since it can be "accellerated" through the problem. Could it be bad injectors or throttle positioning sensor? Any help would be GREATLY APPRECIATED.