Some of you may remember this question from a few months back but since then I've done some more investagating. I was towing a trailer. (empty) My truck was running fine. After about an hour on the inter state the check engine light came on. I checked the gauges temp was pegged at hot oil pressure was at Low. I pulled over and shut it down. Upon checking the water it was full. the oil level was fine but the engine was definatly hot. When I cranked it back up after letting it cool off the oil level said normal until I revved the engine hen it would go down. There is some valve noise also. Once I got it home after a few days I cranked it again oil pressure stayed good even when revving. But there is some valve noise and a harder heavier knock. I'm not sure if it is a rod or not. I've pulled the belts to eliminate everything but the internal engine still the same, I pulled the plug wires one by one it does'nt have a dead cylinder and noise isn't quieter.The motor still runns good and strong. Whats the possibility its a lifter or something? Upon revving it up I hear 4 knocks. then it quiets. I thought a rod stayed the same just got faster? Any ideas Would be appreciated I really need the truck but don't have the money to just start trying things.

thanks Alan

93 F150 300 six EFI
5 speed 118,000 miles