If the compression is good, and the valves are adjusted right, and the firing order is correct, I would guess you have somthing in your intake or head. are all your red rags present and accounted for? Take it from s
someone who knows, an engine wont run right if a red rag gets down in it! Heres another one on me, I keep 8 racket balls in the velocity stacks on my hilborn setup, I was in a hurry to get loaded one morning and jumped in the car to start it up and load it. It wouldn*t fire a lick, and it sucked those racket balls all the way to the butterflys!