Misfire? Predetination? Distributor?

heres the deal. I have two problems possibly unrelated possibly related. First is a week ago i blew a fuel pressure regulator. SO i changed it and i threw a new fuel filter on for good measure. well since i put the new fuel filter on it takes almost 5 times as long to turn over. Also as of reasently around 35 mph if i floor it the engine hesitates to the point where if feels like its going to die and the ocacionaly gives a pop or two that seemes to resonate from the exhaust or maybe a misfire. i dont think its a misfire because its not that loud. possible fule kink or would it have somethign to do with the ignition such as the distributor or maybe a vacume issuse. has anyone had this problem. btw its the 4.0 inline.
JOhn