350 TBI High Idle Problem

[skyd]

My 93 350 TBI has a strange high idle problem I can't figure out. It has been an issue on and off for about a year, but has finally started to be an issue almost every time I start the truck. It would happen once and a while then not do it again for months, but now that it is doing it consistently I figure I might be able to figure it out. The truck will stay in high idle (about 1800 rpm in neutral/park and 1000-1100 in gear) until the truck warms up then idle returns to normal (Usually about 10ish minutes). It doesn't effect anything other than the idle. The truck still shifts at the normal rpm and drives at normal rpm. I've replaced the IAC and CTS (AC Delco oem or professional parts to try and avoid faulty parts) and haven't been able to find a vacuum leak. There may be a vacuum leak I just haven't found it. Has anyone had this issue or any idea what might be causing it?

 

[Dylan Pope]

My truck had high idle once,it was like it was still wanting to go when you were stopped,I got some carb and TB cleaner and sprayed into the intake with it running,I just sprayed until the truck was about to die,did about half the can and after that I never had high idle issues again...maybe worth a shot