I replaced the idle speed air control acuator. The truck was idiling very high RPM,s when starting and was shutting off driving and when parking. The new part helped while driving but continues to stall when taking off . There is an adjustment screw on the throttle which I have adjusted to keep the correct idle speed but it doesn't help. When starting the idle speed is still very high. Is there any adjustment for the low idle speed. Help.

 

You most likely have a vacuum leak instead of an idle control problem.

Post the year ,engine ,transmission of the vehicle so everyone who will try to help is not working in the dark with the lights on .

 

1985xlt 2.8l with auto transmission. I have checked all of the vacum lines. I do hear a noise which sounds like a vac leak that goes away when i push on the brake pedal. What is the best way to check for a vaccum leak? Thank you for your reply >

 

best way to check for a vacuum leak is a bottle of soapy water. spray your vac hoses down, they'll bubble if theres and leaks.

 

Remove the hose going to the brake booster and plug it off. If that makes a difference there is prob a leak in the diaphram.
Spraying the hoses and connections with soapy water only works with pressure coming out , not vacuum.
Try taking a propane torch , UNLIT !, and apply the gas in small amounts to the vac connections with the engine idling , any change in idle will pinpoint a leak.
Take your time and don't wear loose clothing.

 

THANK YOU I WILL TRY THE SOAPY WATER.

 

I WILL TRY WHAT YOU SUGGESTED IF THE DIAPHRAM IS LEAKING ON THE BOOSTER WOULD THAT CAUSE A PROBLEM WITH THE IDLE? THAKS FOR YOUR HELP.

 

If I need new vacuum lines where can I get them?

 

The idle speed is ok when I plug the vacuum booster hose. Is there anything else I can check before I get the booster? The check valve on the booster is ok. Thanks for any help.