My Monte idles high sometime and stays there, then eventually revs back down, lately it revs normal then once you accelerate it revs high gets stuck and keeps accelerating without my foot being on the accelerator and it's hard to stop even with the E brake on, I've almost crashed on several occasions today because it wouldn't stop and keep accelerating, I finally got it to stop(hoping I didn't ruin the tranny) I threw it in neutral and managed not to run into my garage did a semi donut in my back yard avoided the neighbors fence and just shut it off once iI straightened it out. I went back out and started it but it's still in high rev(very high), Also before this started happening it would just shut off while driving at a moments notice. I was told there was a recall on Monty's that shut off while driving but I didn't see any for my year unless I missed it. Any and all help is greatly appreciated.
Hutch

 

What year Monte and which engine? Any service engine codes?

I feel like you have one of three possible problems:
1. - Problem with the IAC (getting stuck in a position that is open further than it should be)
2. - Something causing a problem with the throttle plate on the throttle body closing properly (such as a problem with a throttle or cruise cable).
3. - Vacuum problem.

Vac leak can be easy to test for. With engine in park and running, mist Starting Fluid around the vac connections and various seals/gaskets of the engine. If there is an issue, the idle will change as it sucks in the fluid from the leak. Then you can pin point the problem.
Make sure the IAC is plugged in (that is a solenoid that is attached to the throttle body). May want to take it out of the throttle body to clean it and make sure it does not have an obstruction causing it to fail. There are other diagnostic steps, but require a scan tool that allows you to control the IAC while the engine is running.
As for the throttle plate, try to watch the plate itself OR the linkage on the throttle body. Ensure it opens and closes as expected. If the linkage is not hitting the designated stop to properly close, try to find out why. Could be the spring to close the linkage is damaged.