someone else ask did you degree in the camshaft. anytime the deck has been cut or the head shaved
the cam will be out of time slightly. an adjustable camshaft sprocket can be used to get it back into spec.
on stock cams this is not as important as aftermarket cams. if this was not done during assembly
it could be the root of your problem. read up on youtube about how to degree a cam. the card that came with the
cam will tell you when things are supposed to happen (opening and closing of the valves). a few degrees
off can make a huge difference and aftermarket cams are more dependent on this being correct.
even if the head is new and the deck is uncut (never built one that had an undecked block) i still degree in my cams.