hey guys thanks for the replies on my first post. got another Q again my truck is an old 87 f150 4.9 300 straight 6 beater that im going to turn into a respectable work truck. when you first start it in the cold it idles good around 1000 rpm. but when it warms up after about 5 min it idles around 3000 rpm. i checked the vacuum resivor its not rusted all the way thru i dont think. my lines look are pretty dry rotted. is there anything else it could be like idle control motor. thanks for the help really helps talking to you guys!

 

Replace your vacuum lines first - if they look rotted they probably are and leaking vacuum lines screw with idle speed.

 

carb or fuel injected? If it's fuel injected make sure you have coolant going into the throttle body, that helps warm the IAC, should be 2 small 3/8ths coolant hoses going to it, for some reason air always traps in there because it sits high in the engine compartment. If it's got a carb, and it has a solenoid that pushes out to raise idle make sure the lever on throttle where the solenoid touches is clean, sand down the throttle linkage and the solenoid, it makes a ground connection there so the solenoid knows it is hitting and controls the idle. Hope that helps, Good Luck

 

Pull codes. Sounds like typical tps problem considering it doesn't idle high at startup, but can't rule out other stuff across the internet.

Codes.

 

thanks guys helps alot!