please help, i blew last engine and just got another block and bare head, put my old cam and old manifolds etc back on it but now when i reach about 5000 revs it misses when i let off its ok about 20 seconds later, took it rolling road and he said when the revs get up the spark goes crazy so i changed ecu, dizzy and coil but still the same, i know the turbo oil seals are gone but could this cause it, any help would be much appreciated