I cant figure this one out. Everytime i turn on the a/c the truck seems to run at lower rpms in drive but runs fine unless i come to a stop then the truck idles lower and lower until it dies. it does it in any gear or park. Any guesses?

 

A couple of possibilities to start you off:

IAC (Idle Air Controller), it's called the ISC (Idle Speed Controller) on earlier trucks. If it sticks, it may control the idle erratically or not at all.

Vacuum leak. It could be anywhere between the throttle plate and the cylinder head. Check the intake manifold and throttle body bolts to see if they are tight. Take a look at the PCV plumbing. Make sure that the closure tube is in position - it plugs into the large intake tube and is easily knocked off during routine servicing. Also, most years have a rubber elbow that often splits when it gets old and causes a leak and a lean condition.

 

i already did check the IAC with no luck but thanks for the rest of the advice ill check it out it cant hurt Is the tube large or small that plugs into the intake tube

 

The closure tube is about 1/2" or so diameter - it's black plastic on my truck. The rubber elbow I mentioned may be partially hidden under the front of the intake manifold or elsewhere on the manifold. It is probably about 5/8" or thereabouts. I'm not sure about the exact layout or details on your 93.

 

Thanks alot im going to go check it out right now