I have a 1995 GMC Sierra 4.3 liter V6 that when you crank it it is idling very high.

IAC? Vac leak? Binding throttle plate?

I do not know what IAC is or the binding throttle plate...or their locations.

The IAC is the idle air control valve....this regulates small amounts of air through the engine when necessary....an intermittent problem with the IAC, or connection/wire in the harness to it, can cause a high idle...

Here is a pic of an IAC....



The throttle plate is located in the throttle body...this is where air from you filter enters the engine,,,,the throttle plate opens and closes via the cable to your gas pedal....if the throttle body is gummed up, it can cause the plate to bind or not completely close, creating a high idle......

A vac leak is un-metered air, that can cause a high Idle also.......could be a vac line, gasket, etc.