I have a 1995 z71 and i took the tbi off cleaned every thing well and put back on with a new iac valve.Now after I drive for a while and stop it idles about 1500 rpm.Any ideas,thanks.

 

um...turn down the idle screw.

 

Don't touch the idle screw. TBI's are not made to be adjusted, that will mess with the ECM and how it controls the fuel/air ratio. I had quite the similar problem with my pickup, it even had an entirely new Holley TBI unit. What it ended up being was the TPS(throttle position sensor). If the TPS starts giving faultyreadings, the ECM goes into a "factory default mode" of about 1200-1500 RPM.Troubleshoot it with a good DVOM. If you don't care for that just try a new one from the store, shouldn't run over $70.

Hope this helps.