Lights dim and shuts off

Hi and thanks for using 2CarPros.

Many things can cause the engine to stall. Things such as an engine vacuum leak, bad or dirty idle air control valve, a plugged air filter, fuel leak and the list goes on.

With that in mind, take a look through the following link. It discusses the most common reasons for the engine stalling.

https://www.2carpros.com/articles/stall-at-idle

If you find the idle air control valve is the problem, here are the directions for replacement.

All attached pictures correlate with these directions:

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IDLE AIR CONTROL (IAC) VALVE REPLACEMENT

REMOVAL PROCEDURE
1. Turn OFF the ignition.
2. Remove the air cleaner outlet resonator.
3. Disconnect the idle air control (IAC) valve harness connector.
4. Remove the IAC valve mounting screws.
5. Remove the IAC valve and O-ring from the throttle body assembly.

CLEANING AND INSPECTION PROCEDURE
1. Clean the IAC valve O-ring sealing surface, pintle valve seat, and air passage.
- Remove excess carbon deposits with a small amount of carburetor cleaner on a parts cleaning brush. Follow any instructions on the cleaner container regarding cleaner usage.
- DO NOT use a cleaner containing an extremely powerful solvent such as methl ethyl ketone.
- Shiny spots on the pintle and seat do not represent a bent or misaligned pintle shaft.
- If heavy deposits are present in the air passage, remove the throttle body for a complete cleaning.
2. Replace the IAC valve O-ring.

IMPORTANT: DO NOT reuse the original O-ring.

INSTALLATION PROCEDURE
1. On a new IAC valve, measure the distance between the IAC valve pintle and mounting flange. Use finger pressure to slowly retract the pintle if the distance is more than 28 mm (1-1/8 in).

IMPORTANT: Use an identical part when installing a new idle air control (IAC) valve. The IAC valve pintle shape and dimensions are designed for specific applications.
2. Lubricate the IAC valve O-ring with clean engine oil.
3. Align the flange holes with the mounting holes on the throttle body assembly.
4. Insert the IAC valve through the O-ring into the throttle body assembly.
5. Install the IAC valve mounting screws.

NOTE: Refer to Fastener Notice in Service Precautions.

IMPORTANT: The screws used to attach the IAC valve are coated with thread locking adhesive. Clean the attaching screw threads and apply thread locking material GM P/N 1052624 or equivalent.

Tighten
Tighten the screws to 3 N.m (27 lb in).
6. Connect the IAC valve harness connector.
7. Install the air cleaner outlet resonator.
8. Perform the IAC Reset procedure:
8.1. Turn ON the ignition, with the engine OFF, for 5 seconds.
8.2. Turn OFF the ignition for 10 seconds.
8.3. Start the engine and check for proper idle speed.

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Let me know if anything here helps. Since it stalls in park and neutral, I suspect there is either a vacuum leak or the IAC is bad.

Take care,
Joe