ALT5

Have a 2007 5.4 4x4. I have only has the truck for a few months. It has never had a issue and runs like a top. Today when I was backing up my 30' trailer it would make a awful knocking noise from the motor when I barely hit the gas to back up the trailer. It did it only once or twice. It makes no noise at idle. Also my truck does not normally move forward at all when in gear. But after its little episode it idled at like 800rpm in drive and rolled uphill easily. I'm waiting for it to cool to double check the trans fluid. It was just serviced. My gryphon never showed the truck was too hot neither did the normal gauge on the dash. No codes on my gryphon and everything was ok when I ran a system check. Need advice