1999 Venture Van Stall / Low Idle

[ronatola]

Hello all. I have a 1999 Venture Van.
The engine has a low idle and stalls when stopped/parked after driving on the highway for 10 minutes or longer. Whenever I drive it to the train station in the morning to go to work, it dies as soon as I park it. It will start up again fine right away tho. I drive 10 minutes on the highway.
The engine light is on, but goes off sometimes for months before coming on again. I've brought it to at least 3 mechanics and they can't get the light to stay permanently off, and say to just drive as-is.
But that still leaves me with the low idling problem.
It doesn't always stall, but the potential is always there, as you can hear the low rpms threatening, and dread stopping at a light.
I had the engine light interpreted as P0122 TP SENSOR CIRCUIT LOW. The mechanic replaced the Throttle Positioning Sensor.
Engine light came on again 2010. Mechanic did a Computer system check/smoke test. Diagnosed a Leak in evap system so they installed a new gas cap and vent valve. 2 months later, engine light went on again.
New plugs, spark wires, fuel filter, fuel treatment, fuel line, gas cap, vent valve.
1 month later light is on again, and low idling persists. I put alot of $ into the problem with no solution.
Some mechanics say the engine light has no relation to the low idling.
Help please. Wife wants me to get rid of it, but the Van is in great condition except the low idling/stalling problem.
I don't care if the light stays on, as long as the low idling/stalling stops.
Can’t I just ask a mechanic to increase the idling rpm?
Any ideas?

[roadrunner2]

Your low idle/stalling problem MAY be due to a faulty IAC (Idle Air Control) valve at the throttle body.

[paprius4030]

Take it to a good mechanic who knows the car. If you can't find any good independent, go to a Chevy dealer, they probably see it all the time.

[lesterl]

I had some issues with the low idle/ etc..... I had replaced the plugs with Bosch single electrode platnium plugs, ran ok for a while, then my issues started, finally re-replaced the plugs with some NGK's and it purr's like a kitten now.......

[ronatola]

FIX UPDATE:
It ended up being the Oxygen Sensor, and the tailpipe threads needed to be fixed.
Absolutely no hint of a stall now

[lesterl]

What was your gas mileage before and after? How many miles again? Had it ever had a bad LIM gasket? Any other major repairs that you know of that may have caused the O2 to go?

[merc81]

I'm sorry I didn't see this thread 'till too late. I experienced pretty much the same thing--my problem got so bad the van would stall while driving down the road during times you let off the gas. Needless to say this drove my wife nuts because the power steering would die with then engine and this usually happened when you slowed to get around a tight bend in the road!

It was all fixed by a new O2 sensor (the one before the converter) although the one I purchased from rockauto didn't work quite right and I got another from Napa. I'm still unhappy about that experience with RA.
Hard to believe that the low idle would be so impacted by the O2 sensor but there you go. . .