My son pressure wahsed engine compartment and ever since that the truck runs at a high idle speed. After you drive about 45 min and stop the engine stalls when you put it in gear D or R.

If you let the truck sit for about 1 hour it runs fine until warmed up again. It will crank but no start. You can smell gas.

Any ideas would be appriciated. I do not know what most abbreviations for under hood electrical components.

Thanks

 

. . .

Check the vacuum line on the FPR. If there's gas (or even just the ODOR) coming out of the FPR nipple with the truck running, replace the FPR. But if he just blew the line off, the fuel smell could be coming from the tailpipe (or any exhaust leak), so put it back & go for a drive.

Otherwise, check for any vacuum leaks using a 3' piece of garden hose as a stethoscope all over the idling engine. A vacuum leak will sound like a LOUD hiss/whistle.

 

While there could be many reasons for your problem I would first check on the "Idle Air Bypass Controller". This could be both the sensor itself, and the wiring up to the controller.
The controller itself is pretty easy to find on top of the intake manifold. While there you can also check on the manifold vacuum sensor which could have been soaked with water down in the intake tube. The sensor, and controller usually sit high on top of the intake manifold, and can be abused by water spray that might get into the intake manifold by the washer spray. They both have small air or vacuum orifices that if clogged can change how the engine operates especially at start up. I can not think of any other unit that would be affected to this extent after this time. They are both pretty easy to remove check and or clean. I'll bet the IAC (controller) has gone bad and would suggest replacement.
Hope this helps.

 

The IAC has no smal orifices, and water can't penetrate its gasket. His '96 has the Hitachi type, but water can't get thru the vent, either.

 

My insistence on checking on the IAC and it's wiring circuit was based on this assumption. The IAC is a controller unit, and if it has failed or become intermittent due to any reason that it has final duty of controlling the engine idle speed.
The power washing job was not described, but I saw an individual actually power wash his engine by removing all of the intake plumbing, and literally blasting the engine totally.
I don't think that this was that extreme, but it was included as a reason for why the car is having a serious problem.
If water has gotten inside the throttle body plumbing by any means then it "could have" clogged a manifold vacuum sensor and even the IAC pintle seat. However seemingly all water should have dried up by this time, but the driver still has the problem. My opinion was to check both the wiring to the IAC at the controller, wiring harness, and the IAC itself. Bad connections from the PCM to the IAC could have been caused by a heavy water stream from a power washer. I see from your diagram the type of the IAC, but if the wiring or contact connections become bad it will usually mean poor idle control.

 

I wouldn't call the IAC the "final" idle speed controller. The SPOUT has at least as much effect on idle speed as the IAC, if not more. There are MANY factors that affect idle speed, and the IAC only controls the air flow.