I am not very mechanicaly inclined so bare with me. I have a 1986 iroc z28. When I go to start car the rpms shoot up to about 2500 and holds and it won't drop down to a normal idle. I think it could be carb but not sure.( also it starts to smoke a little from carb) I have a edelbrock 1406 on it. But anyway for the other part of the problem. When I go to shut off the vehicle it acts like it wants to keep running then kinda shakes then shutts off any help would be great. And ps once I start it up it gets warm/hott quick. This has never happend to me before outta the five years I've owned it.

 

Welcome aboard thirdgen.org.

The 1406 should have an electric choke. Any idea if it's working properly? It could be that it has been for the last 5 years, and now it is no longer opening properly. The choke engages a fast idle cam, and if engaged while the engine is warm, it'll result in a high idle and "run-on" when you turn off the ignition.

That's assuming nothing was done/changed to the engine before this started happening.