I have a 2002 5.9L 4X4 with 94,000 miles. back in march I had a problem with it stalling out when the gas was lifted, so I changed the IAC valve. Worked great untill this morning, driving at 40MPH lifted off the gas to brake and the RPM dropped below 500 and stalled. I was able to restart and continue, I also floored it and it seemed to have temperally fixed it for the rest of the drive. I was told it could be the MAP sensor or TPS, no codes, can the IAC valve be bad already, and if so why. Hoping anyone can help so I dont have to go buy the whole parts store. Thanks

 

The IAC insnt bad, try a new tps.

I put in a new IAC and things were good for a moment. A new tps fixed my problem.

 

i would look at a new TPS first if you already replaced the IAC, but it is possible that you just got a faulty IAC when you bought it, although i would have expected that problem to show up much much sooner than you say it did.

 

I'm thinking a new a TPS, but did you clean out the Throttle Body and reset the PCM bwhen you installed the IAC sensor?

 

Thanks, Replaced the TPS and reset the PCM, runs like a champ again.

 

Spoke to soon. Went to get gas this morning and when I restared it it would not idle. Had to restart it twice, but when I finally got it going, I stomped on the gas got it up to 50MPH, and drove it home about 3 miles, ran good after that. So I am assuming its a bad IAC valve? Should I change that, cause I am out if ideas.

 

Either that or a bad battery.