well, I finally have the old beast running and driving, unfortunately it has an outrageously high idle even well after warming up, and I don't know how to fix it. A short history, I put a 5 speed out of an 88 into an originally automatic 87, currently running on the 87 auto computer. If i put the 88 5 speed computer in it would that help. If not what do I need to do. The truck does not have a tach, but I'm guestimating the idle is well over 1000 rpm

Thank
Greg

 

Fuel injected engines use an air valve to control idle, no Jets
Ford calls their valve the IAC(idle air control) Valve
Its a simple solenoid valve, 2 wires, it on upper intake next to the throttle plate, its on an air passage that by pass the throttle plate
Looks like a can on its side

With engine idling unplug its 2 wire connector, valve should close and idle should drop to 600 or so, or engine may even stall
If idle stays high then you have a Vacuum leak
Did you plug the vacuum hose port that went to the automatic trans modulator?
Is PCV Valve OK and connected?
Power brake booster hose?

Using automatic computer can cause wandering idle and idle would be slightly higher than manual computer
Manual should idle at about 650, auto 750, after warm up

 

Thanks, I'll check these when it stops raining.

 

once again you're spot on, vacuum line was just laying in with the plug wires, pushed it onto a bolt sticking out of the firewall, and the idle dropped right down, this week i'll change the computers to stop the slight surging.

Thanks
Greg