I'm gonna go out on a limb here, as this is rare...BUT, before you freshened the engine, did you wipe the trans or converter? If so, the crankshaft could be "broke", cracked, whatever you want to call it. The impact from the converter, front pump on trans can break a crank. I know folks whom have seen the same symptoms after a trans failure. PM supercomp...he been there, done that.