i just had the head serviced, vavles ground and head surfaced. i reinstalled the head and the car fired right up and idled fine. when i tried to rev it a little ,it falls on its face, just nothing although if i get the rpm s up to about 2000 to 2500 rpm s it seems to run great for about 5 seconds and then its like a no fuel situation . could this be caused by improper valve adjustment ?