I had a carb shop build me a non-CC Q-jet. I installed it along with a performer RPM Q-jet intake. It has been running fine for 1 week but all of a sudden the other day it started idling really high and I'm watching the tach and the RPM's were really twitchy. Also it smelled rich for no good reason and lots of white smoke was coming out from the back. I really don't know what it could be.

 

Choke heater wire come loose? Check your choke action along with fast idle cam.

 

sounds like you got an intake manifold leak
- vacuum leaks gives the high idle, coolant in intake gives the white smoke.

 

Yeah, make sure the choke wire is hooked up and supplying a full 12V. I assume it's an electrically heated choke. If not, it will not fully open and stay up on the "fast idle cam" that's part of the choke linkage. Really, any reason the choke isn't opening fully (or the linkage isn't working for whatever reason) could cause this.

A vacuum leak, maybe, but it would have to be a situation where a vacuum hose suddenly slipped off for it to be a problem that cropped up like someone flipped a light switch.