Ford Repair: idle, worse case scenario, air control valve

Question
i have an 89 bronco with a 351 5.8 engine.it idles fine after starting but jumps up to 2000 rpm as soon as i touch the gas. the check engine light has been on since i bought the truck and runs fine when on. when it jumps to 2000 the light goes off and will stay off until the idle goes back to normal.

Answer
Remove the idle air control valve and clean it and the throttle body. Take car removing the Iacv not to tear the gasket. Use Air intake and idle air control valve cleaner, a cloth rag that isn't dirty, but can be thrown away. A tooth brush and some elbow grease. Your double air intake places the butterfly flap further back than your non truck EFI engine. Cleaning is always recommended every other oil change. You will be disgusted when you realize the gunk. After cleaning, pull the negative cable for at least 15 secs. Resetting the code will allow you to know if it is another sensor, which it likely is not. Worse case scenario is that the Iacv itself got so gunked up, it needs replaced. It is literally nothing to yank one of those off, so installing the old cleaned one is well worth replacing the part that works just fine. Or, you can buy a new one, and know for sure that the problem will be fixed. Of course you still need to clean out the throttle body either way.