1999 Chevrolet Monte Carlo

Engine Performance problem
1999 Chevy Monte Carlo 6 cyl Front Wheel Drive Automatic 96410 miles

my car will start fine but will not stay running unless I stay on the throttle.
I noticed previously today, that when I attempted to pass another vehicle my throttle barely responded. I backed off the accelerator and push it about four times before it responded.
I parked the car for about 2 hours or so and then drove it home. I stopped and got gas, got into my car and when I started it, the RPMs raised like normal, but fell back to zero immediately.
If I start my car I can keep it running for as long as I want, IF I keep the RPMs above 1500.
Brad Eadens
October 24, 2010.

NOTE: Idle speed is controlled by PCM and is not adjustable. Slight fluctuations in idle speed are considered normal. Start and run engine for at least 7 minutes to establish PCM control of idle.

3.1L, 3.4L, 3.5L, 3.8L & 4.0L
Idle speed is PCM-controlled. Resetting of IAC valve pintle is the only adjustment that can be performed. To reset IAC valve pintle position, turn ignition on.
Turn ignition off for 10 seconds. Start engine and check for proper idle operation. Repeat procedure if proper idle operation is not obtained.

Check following items: Ensure throttle linkage and/or TP sensor is not sticking or binding. Ensure throttle bore is free of foreign material.
Check for vacuum leaks.
Check engine idle speed (both base idle and PCM idle).
Check Idle Air Control (IAC) system. Check for vacuum leak or high idle. Check for water contaminated fuel, correct fuel pressure or a restricted injector
Check for proper spark plug gap, and check engine compression.
Check PCM grounds for clean and tight connections.

Check exhaust system for restrictions, such as a damaged or collapsed pipe, muffler or catalytic converter

Oct 24, 2010.
Kinda confused about the answer: I tried to start the vehicle but it will not stay running. It starts like normal, but as soon as the RPM gauge goes to approximately 1000RPM, the RPM gauge falls back to Zero. I can keep the car running if I use the gas pedal and keep the RPMs above 1000, but as soon as I back off the throttle the car dies.

Brad Eadens
Oct 25, 2010.
Check : if have a vacuum leak
if have a bad idle air control
base idle
for codes

Oct 25, 2010.