While driving home a few nights ago, my truck suddenly died. It was not running hot, and there was no smell or smoke. Oil level was/is still normal. We found that the battery was bad, replaced it, and still no turnover. We then replaced the starter relay (on the firewall) and the starter. Still the same. The truck acts like it wants to turn over, but then something stops it. Any help would greatly be appreciated...this is my only vehicle.

Truck is a 2001 F150 5.4 4x4

 

put a socket on the crank pulley bolt. make sure you can turn it over by hand with a ratchet or breaker bar.

post a video of what happens when you try to crank it over.