I'm having a problem with my Holley carb (750 CFM vac. secondary) that I've never seem before. I just replaced the vacuum booster on my truck because it had a bad vac. leak and then I swapped my Edelbrock Carb out for my Holley. When I tried to start it, it wouldn't start unless the throttle was to the floor which made me think it might be flooded. I let it sit for about an hour and tried again with the same results. Once it started, it ran fairly rough for a few seconds then seemed to "catch up" and when I let off, it died immediatly like I turned the key off. Tried again and if I held the throttle about halfway open after it started, it would run rough at about 1000 RPM. It won't even try to start unless it is all the way to the floor. It starts fine with the Edelbrock, but runs poorly. Its an old carb.
I checked for vac. leaks and found none. I just rebuilt the carb (Holley). Float level is set to spec. Idle screws are 1 1/2 turns out. Accelerator pump is new. Power valve is new with blowout protection.
Any ideas?