I have a Edelbrock 600 electric choke carb and have had excellent results but have noticed lately that if I let it idle to warm up it starts to load up on me and sounds like it has a wild cam in it?? During that time the choke is off. If I look at the vacuum gauge it's bouncing pretty good. As soon as I drive it she's fine again and won't do it anymore. It's on a 79 302

 

How many turns are your mixture screws turned out? is it running rich at idle?

 

Actually I've never messed with the mixture screws. The only thing I did lately was up the fast idle speed but I will tap the accellerator to release the fast idle after a minute or so and that's when it starts to load up.

 

You may want to check where they're set at, turn them in until both screws seat (gently) then back them out 2 turns to establish a baseline, using your vacuum gauge adjust for the highest possible vacuum reading at your set idle speed by turning the mixture screws in 1/4 turn increments (adjusting both screws the same amount).