Its pretty common in preused engines. Alot of time the previous owner didn't know what he was doing when tuning it and therefore just set the needles so it would idle a long time without building up too much fuel and killing the engine. But at the same time, the top end is robbed and extra wear and tear on the engine takes place. I've been there myself and have been guilty of doing the same thing in past engines. But the tuning bible set me straight and i haven't had an issue since.