is this a timing issue, a compression issue, gas leaking into the engine? curious as to how i can fix this issue. i have timing set to at 4~6 btdc, idling around 750 rpm, with a holley street avenger 4 barrel.

 

does it knock/ping when its running? Did you put some bad gas in it? Winter ethanol gas?

 

fresh gas, dont hear any pinging or knocking while its runnin

 

If you are talking about something called run on or dieseling where the engine seems to want to continue to fire and run roughly with some noise, it could be timing or gas.
If you are talking about turning the key off and the engine just quietly rotates to a stop with a smooth and even reduction in RPM, it's probably loss of compression.
Terry

 

I had this going on with one of my cars a while back and found that reducing the idle speed to about 700rpm stopped it (670 Avenger in my case as well - not that it should matter). Also - make sure your choke is completely disengaging - if below 30 degrees out I have a tough time getting mine to release even when engine temp is 180 and still after I've adjusted it several notches. If choke is on it will definitely cause this run-on situation as well. Timing can also definitely be a factor.