Help: 1988 GM 5.7 TBI high idle

im hoping that your talking about a truck .... but if your wondering about a high idle it could be a few different things... there is either a vaccuum leak somewhere like the elbow running to the pcv valve is common, it could also be that the ignition timing is out. i would check all of the hoses running from the throttle body for leaks, pull out the idle motor and clean it with a throttle body cleaner and see what that does for you. if nothing happens or you find no leaks try checking the ignition timing

**make sure the zero timing wire is disconnected its a tan wire on the firewall near all of the relays under a black cover** with this wire disconnected the timing should be set to 0* then reconnect the wire... thats about the extent of my knowledge without seeing the thing running in front of me so good luck!