Hey, My 1999 Ford F150 5.4 V8 has a low knocking noise. It starts when I start the truck, goes away when I start going a little but if I rev it the knocking gets worse. The oil pressure stays fine, so I thought it might be a crack in the flex plate. It could be a rod bearing as well, but I really don't know. I took it out on the freeway and it sounded like it was gonna explode when I got up to around 75 mph. Any suggestions, theories, or remedies to make my engine last a little longer would help.