2000 Durango hard start

I just finished a tune-up on my 4.7 2000 Durango. The original problem is that it cranks over for a long time when trying to start the motor. It will crank for about 10 seconds b4 it finally fires up. However it always starts, just takes awhile. I thought possibly a partially plugged fuel filter, and considered changing the filter, until I found out it was in the tank. Any help would be greatly appreciated!!!!! Thank you!!

You probably need to connect a fuel pressure gauge and watch for a fuel pressure drop in the system, possible a bad pump or leaking injector