make sure the eddy spring tension is not stuck on the throttle shafts
make sure it not hitting/hanging up on the intake at the carb base
I had trouble with one hitting the choke well and had to use a 1" spacer to lift the carb so linkage would clear
what he said on throttle cable
unhook it and try
the choke linkage and fast idle cam is out of wack maybe
manual curb idle screw is not in to far correct?
seems odd 2 diff style carbs do the same thing,make me think its something mech or a vac leak
pcv hose tight,missing a cap on vac port???
plug in the back for the brake vac port
brake vac booster good and not leaking??