High Idle Problem
I have my beloved 1988 GMC 4WD ext cab K1500 5.7 Throttle body. The truck starts good, and idles smooth. Problem: The longer it runs, the faster it idles. At times when I stop and put it back in gear when it is running so fast, it dies just as soon as I put it in gear. Re-starts, but high idle.
Also, my heater doesn't switch from heat to defrost. I am assuming it is a vacuum problem, and the two might be related, but I cannot find a bad hose or leak anywhere. Any suggestions on where to start or what to check?