1996 Chevy Lumina help Lumina idling issue

Thanks in advance for your help :-)

I have a 96 Lumina 3.1 v6 engine. 2 years ago I had new head gaskets and new fuel regulator/fuel pump replaced on car.
Everything has been fine, however, after going about 200 mile trip the next time I got in my car to pull out of my driveway it did a little "bucking motion" in reverse and since my RPMs have been high.
When I start the car we are @ 1000rpm and when driving I'm shifting at the high end 3000rpm when my foot is on gas and stays around 2300rpm, when my foot is off it seems to settle around the 1500rpm where it normally has been.
I was wondering if anyone had any information that could help me figure this out! No check engine light. My coolant level is fine and so is the oil!
Thanks again!

Crystal