weird Idle problems...

Hello everyone, I am jumping over from the toyota form to help out my uncle with his 95 4x4 Surburban. He says that when you first start it up the RPM are very high and when he drops it in to drive it throw the gear really hard and it shift hard too. But when he turns it off the RPMs are back to normal and it shift fine with no problems. What could this be? Any help would be greatly appreciated.
thanks
chris

Check for trouble codes first. Then test the TPS, IAC and MAP sensors.

A high idle could also be a TBI gasket leaking. This was a real common issue until they redesigned the gasket.

Also check for any broken vacuum lines.

//2000CAYukon