Engine stalls at idle?

Other than replacing the IAC (idle air control valve), this could be a trans problem. Also check the motor mounts for excessive engine movement when reverse is selected. This sounds like you have a vacuum leak, dirty throttle bore or the IAC motor is not working but to be sure lets check out these guides to help us fix it.

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

and

https://www.2carpros.com/articles/throttle-actuator-service

and

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Please run down these guides and report back.

So when you have the brakes on, the engine stops as if you turn the key or it falters and stalls? If it is the latter, you will probably have a faulty brake booster.

The check valve is plugged into the booster, see pic and look at your booster.

It should be easy to replace, have you done that yet?

Try cleaning throttle plate on both sides and IAC hole with choke cleaner.

Okay, well not knowing that is the first thing I recommend. check fuel pressure with a gauge may be low. auto parts rent gauge.
https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Hi,

The first thing I would think is the ignition is affected by the moisture. Do me a favor. When this happens and it won't start, check to see if there is spark to the plugs. Here is a link that shows how it's done:

https://www.2carpros.com/articles/how-to-test-an-ignition-system

If there is no spark or a weak spark, the first thing I would do is check the distributor cap to make sure it is tight and has no cracks. Also, check to see if the ignition plug wires are in good condition as well as the coil wire to the cap. Have a helper crank the vehicle and see if you notice anything sparking. If you have some down time, open the hood, start the engine, and lightly mist the areas I mentioned with water to see if it causes a stall.

Picture 1 below shows the distributor cap.

Do this and let me know what you find or if you have other questions.

Take care,
Joe

The main thing that is going to affect starting or running when wet is the ignition system. So we need to pull a spark plug and check for a strong blue spark. I suspect you have an issue with the igniter or the coil itself. If you have spark but it is not strong or is even yellowish in color then most likely the secondary side of the coil is the issue so you are not getting the high voltage spark that you need.

I attached the basic info about this system. Let me know what you find with the condition of the spark when this is happening and we can go from there.

Check the Idle Air Control valve, they get dirty and can get stuck. Also check the EGR valve, they are not supposed to operate at idle/slow speed, if they open at idle, they will generally kill the engine.

Also make sure the torque convertor clutch is working properly, they engauge at 40-45mph, so you should feel the rpm's go up slightly when decelerating from 55 to 40-45, If not the TCC will kill the engine.

You can feel the TCC engauge when accelerating (smoothly) at 40-45mph. It will shift into high gear then you will feel a small "bump" when it locks up, you should also feel it disengage.

Check the wires to see if there is a crossed wire, If you deid anything withe the plug wires it sounds that two spark plug wires are crossed. That would cause the misfire and ping. Just by reading your post to me that is what happened.