Need more info. your question is a little too generalised. I can think of countless number of things that would cause an engine to run poorly so lets try to narrow it down a little bit.
Is this the first time it has ran since the rebuild? Or it ran great last season but this year it doesn't
When you say it runs to 3k and quits do you mean it quits running completely ? or it runs, but 3k is all it will spin?
C.T. :wink: