what engine, 95 ej22 ??
did you ''prime'' and clean the HLAs before you installed the engine?
i have heard of the giudes? dropping? whatever that means. but it is so rare i have not heard of the cause. so maybe that is your problem but i would double check everything else twice before you starting in this direction.
are all valvse standing open? or just intake, or just one side of the engine?
are the cams the same ones that came on the head?