Holley tuning Question

[Mark Brye]

I have this problem with my 770 Street Avenger carb, that when the engine gets warmed up, after an hour or so of driving, the idle seems to work its way up. When some what cold, or after reaching operating temperature and running for a half hour or so, the idle is perfect at 800rpm. I come to a stop and it settles right down to 800. I can stab the throttle and do anything with the right foot and it settles down to 800rpm. Then after about an hour, if I come to a light, it will be up around 1300rpm. If I stab the throttle, it will return to 1300rpm or so. Then after idling for several minutes, it will sneak its way back to 800rpm. What could be causing this? It’s not bad to drive, its just real annoying. It seems to happen more often with warmer temperatures outside. I also seem to have an issue with the car wanting to “diesel” when I shut it down after a long trip. This does not always happen, but sometime the engine wants to keep running for a revolution or two after I turn the key off. Most of the time it just shuts down but its really embarrassing when I do go to shut the engine off and it trys to keep running. There is no spark when I shut it down so it sounds terrible when this happens.
Any ideas would be greatly appreciated.