Just recently bought a 87 F150 Lariat. It is 302, automatic and 2 wheel drive. The truck has 69,000 miles on it. The gentleman who bought it new passed away and his son has had it in his basement for 7 years. We are currently replacing all the steering parts, ball joints, brakes and exhaust system with a duals. The main problem no is when you start it, it revs to a very high idle, you can pat the gas peddle and it will idle down. When the engine warms up its fine. Sensors replaced so far, TPS, OXY, and cold start sensor. None of these changed the high idle at start up.
Any help will be appreciated.

 

It is supposed to have a somewhat fast idle until it is warmed up. How fast is the idle? It probably doesn't have a tachometer?

 

Does not have a tachometer, guessing around 2500

 

Welcome to the site!
Suggest to check the idle air control (IAC) solenoid for gunk or obstruction, known to be an issue with these model years. About the size of a roll of quarters, with an electrical connection on one end, straddling the throttle butterfly. Carb cleaner works well to clean, make sure the plunger piston moves freely without hitches in the giddy-up across the range.
Good luck, and keep us posted.

 

Thanks for the replies,
I just had surgery on my arm and as soon as I can I am starting back on it.

 

I am having the same issue. Idle air control valve works fine, idles down when you unplug it. I will keep replacing stuff and let you know if I find the magic cure.

1988 F150 4.9L inline 6 EFI

 

Throwing part$ at it is NOT likely to fix it before you run out of money. If you can't diagnose it, pay someone who can. It'll probably take less time & money.

 

mine was bad intake gaskets causing a vacuum leak, and burned valves and warped heads but that was from the overheating the high idle was the lower intake bolts were all loose except two.