GM-GMC: 1996 GMC 4x4 Truck, vacuum leaks, gmc 4x4

Question
The engine is a 305 and idles at 2500 rpm. The truck has 294,000 plus miles. Have checked for vacuum leaks and have found none. I cleaned pvc valve and made sure it was working. Backed off the idle screw at the carburetor to the point that the butter fly sticks slightly when fully closed. Any ideas

Answer
The first thing that I would check is your idle air control valve.  Make sure it isn't stuck in a bit, or that there isn't a piece of carbon or something else in the passage way causing the valve to stay open.  Your IAC is mounted on the throttle body.  You should try to put the idle screw back the position it was before if you can.
Hope this helps