1989 rough idle and revving RPM

[newnthused]

V6 manual transmission. I bought this truck recently and things were fine on test drive. I took it to get smogged and the mechanic said he wouldn't even try to smog it because the idling RPM was too high.

I changed the oil and cabin air filter(there wasn't one). That lowered the idle rpm a bit.

I then cleaned the IAC valve with carb cleaner and made sure not to flip it upside down to avoid damaging IAC motor. That maybe helped a smidge.

I took it back to mechanic and asked what I could do. The mechanic said there may be a vacuum leak and to check the intake. But they also said to start by changing spark plugs.

I changed the spark plugs and the engine started revving higher at idle. I then changed the spark plug wires. Engine is still revving high.

Now when at idle the truck is revving high then makes a clicking noise and sounds like the engine shuts off (or at least stops revving) and rpms drop to 1000, then sort of catches it self and revs up high again. The tachometer is basically jumping between 2000 and 1000 when this clicking happens.

I cleaned the throttle body with throttle body cleaner and this is still and issue.

The clicking sound is coming from a thing that's to the driver side of the engine with several belt systems attached to it. The belt that is clicking a stopping (or skipping?) has a belt that has "AC' written on it. I'll try to include a picture.

Thanks. I would like to get this truck properly smogged and working.

 

[RobbieD]

Welcome to TRS.

You're pointing to the air condiioner (A/C) compressor.

It should only cycle when the climate (heater, or HVAC) control is in "Defrost", or if the "AC" button is pressed.

Check your HVAC controls, and get the AC compressor off while you troubleshoot your idle problem. Get the idle sorted out first, then address the AC.

 

[newnthused]

Do you have any suggestions on the idle fix? I cleaned IAC valve and throttle body. Vacuum leak maybe?