Can't get it to run right

[the-wreck]

Hello guys and Gals

Out of desperation Im bringing my running problem to this excellent board. I put my truck together recently and can't get it too run well. Its a 350 that ran well before I removed it. Basically all I did was change the cam and carb and clean it up.

Its a 350 with a performer rpm, 600 holley vac. secondary, stock hei dist and mild cam.

It has no power. Part throttle it runs well and it idels well too. When you give it heavy throttle it breaks up and sounds like it drop 4 cylinders. I have worked on tons of smallblocks and have never experienced this. Even had a shop look at it and they recommended a carb (which I tried with no luck).
So far I tried different coil, carb, plugs, valve adjustment, timing adjustments and even tore the timing cover off to check the cam/crank marks (there good).
Im thinking of looking at the HEI dist. next. It has an old module in it as well as pick up coil. I put a new adj. vacumme advance in it but adjusting it has no effectr on the problem.
Any ideas?