About 7 years ago, my Camaro went into extended hibernation. There was no fuel in the carb or tank at that time. I recently replaced the fuel pumps - in-tank and mechanical - and the car fires up, but will not idle down. It's idling anywhere from 3500 to 4500 RPM.

Another note, when I turn the key off when the car is idling that high, obviously it is not pretty. But when I try and start it again, the car is really hard to start.

Any ideas?

Was the fuel drained before the car went into hibernation, or just wasn't much in there and it evaporated away?

Very likely the carb is gummed up.

I just thought I'd reply about what may be the solution.
Could rotten vacuum lines be the issue? I replaced four of them today, and it now idles where it should. I don't think I changed anything else.

Sounds like your electric choke might be sticking, if it happens again....

make sure secondary plates arent stuck open.sen it before and really only thing i can think of that would make it idle that high.try snapping them open real fast .this usually makes them release.

I had a similiar issue with my Qjet. On mine it was the mixture control solenoid.
It would rev high and when I restarted the car I had to open up one pair blades to get it to start. this was about 10 years ago so I don't remember which blades I had to open.
I ended up swapping to an Edelbrock 1406 carb

here is a kit to fix your MCS if that is your problme,
http://www.carburetor.ca/carbs/parts...bs/mcs1001.htm

Good to know you fixed it.