Toyota Repair: 1992 toyota 4runner stalls, air intake hose, throttle position sensor

Question
I own a 1992 Toyota 4runner 4WD – 3vze engine - V6 - 3.0 L – Automatic transmission – 84K miles.   The engine starts fine in the mornings, at once, but as I drive the car during the day the RPM gets set in about 500 or less (too low that you can feel it) and the engine will begin to stall when idling (on stop signs, traffic lights or when parking it), it starts fine again but the problem will continue to happen at times in the same ride and it only happens when I have my foot off the throttle pedal. I does not happen every time but very often. So, I turn on the Air Conditioner and the car will drive just fine, it won’t stall at all, as long as the A/C is ON (RPM goes up and set at about 1000 RPM or a little bit less). I hope this makes sense to you, I live in Colombia South America and it’s hard to find the solution to this problem without losing a lot of money on trials and errors. Thank you very much for taking the time to read my problem; I’ll be looking forward your opinion.

Answer
Ricardo,
First check all wire connections to all sensors under the hood.Check all vacuum hoses for cracks or broken, including large rubber air intake hose to the intake manifold. (the clamps loosen over time, you must remove it and inspect it completely 360 degrees for cracks). Three sensors should be tested with an ohm-meter. Throttle position sensor, coolant temp sensor, and air intake sensor.
A repair manual will tell you how to do this.

If there is a auto parts store in your area, ask them to hook
up a scanner to the vehicle.