Please diagnose my stalling issue at warm idle

[winger]

I have a 1999 5.9L 4x4 with 195K miles.

My issue is once the truck has driven down the highway and is good and warm, it will stall when at idle (1,000 rpm) like when i pull up to a stop sign. It only stalls when warm. It does not spit and sputter, it will just die like someone turned the ignition off. All gauges read fine. It will start right up again with no hesitation but will die again if i don't keep the rpm's above 1,000. If I let it sit and cool down for, lets say 5 minutes, it will idle just fine until it gets warm again.

I have replaced the spark plugs and the Idle Air Control Valve. The IAC was crazy dirty. The air filter is good.

Any suggestions before I give in and take it to a mechanic?

 

[Okiespaniel]

I woulda said coil or coil wire, but you say it restarts...so maybe a vacum leak?

 

[ParrotHead FA]

Sounds like what mine does when the sensors in the throttle body get dirty. Mine won't stall if I'm driving it, but when I try and start it after it has only been turned off for a few mins when the engine is hot, like when stopping for gas, I have to keep my foot on it for several seconds and not let the rpm's drop below 1000 til it will idle on it's own. I had contacted my dealership mechanic about this, and he said the sensor (don't remember exactly which one) can get some buildup on it and it will cause this. He said he'd just be taking my money, and told me to remove the air filter housing and open the butterfly and spray all the way around the inside of the throttle body, then afterwards, start the engine and hold the rpms up until it stops running rough. After it's idling properly, spray some more cleaner down the throttle body throat while revving the engine to make sure any buildup is flushed out. He said this problem is not too uncommon after 30,000 + miles of driving on the 97-98 models if the throttle body has not been cleaned. It ran perfectly after I did this. Of course, I got lazy and sure enough, after I'd gone around 35,000 or so since the last time I sprayed off the throttle body when doing a tune up, it started to do it again. A trip to the neighborhood autozone for a can of TB cleaner fixed it right up again.
Dave

 

[Brighton ram]

Sounds like coolant temp sensor,quite common.

 

[winger]

I just replaced the Throttle Position Sensor and no luck. It actually idled a little rough with the new sensor.

Any chance it would be one of the o2 sensors?

I don't really feel like keep spending $$ on a bunch of parts just to rule out a part and try another.