Should I re-prime my new motor after 3 weeks??

At the very least I would undo the coil wire and with the throt. all the way open (at cranking it shuts off the inj. IIRC) crank it over until you get oil press if you have a guage. If you dont crank it for 45 seconds to a 1min and you should be good to go.

That is what I do after the winter slumber anyway.
 
I am not 100%, I recall a conversation with the wifes uncle who is a good sr master ford tech (he is the guy that has to fix what other techs can't fix). He mentioned that while cranking to start with the gas peddle floored it shuts off the inj. pulse so you dont flood the motor. He thought our eec should have this as well. I think I may have read it somewere online as well (we all know the internets is the truth....right?).