2.9 with extremely high surging idle.

[SD95turbo]

The truck is a 1988 Super Cab 4x4 Ranger with the 2.9, 5spd, Factory dual fuel tanks, and a bunch of new parts. I parked the truck a year ago because it started missing. I was driving 75mph down the interstate and it started to miss but would hold that speed easy. Slowly over the next 20 miles it got weaker and weaker to the point it wouldn't even idle in nuetral. Changed the plugs, wires, cap, and rotor beacuse it needed it and I thought this might correct the miss. I didn't. Did a compression test, all checked out great; checked for spark, had it on all; so I assumed it must be an injector. Last night I went to replace the injectors and came across the intake air temp sensor (I believe) wires were melted through and melted together with the injector wires on holes 2 and 5. I fixed the wiring issue and replaced the entire fuel rail and injectors. Purged the system and it fired off on the first try. Now it idles up to around 3k and stays there pretty well it'll surge up a little and every once and awhile it'll come down to the 900 to 1000 range for a second or two. What could cause this? And what is the ideal rpm at idle? New to these 2.9's. Also needs to be timed I think.
Thanks,
Josh

 

[SD95turbo]

Anybody?

 

[freedom5]

You might try cleaning the throttle body and either replace the idle air control or clean it. I replaced mine. Also the TPI (throttle position indicator) can cause your problem. They aren't expensive. After cleaning and/or replacing the items reset the throttle cable just so it will keep running at about 700 - 900 RPM when the idle air control is disconnected. Hope this helps.

Freedom5