1988 Ford F-150 knocking sound when driving

I have a 1988 ford f150 302 5.0 liter FI w/373,000 miles on it. A month or so ago. It just died so I put it in the shop. Was told cause was ignition module. Mechanic changed it and ignition coil. Once I got the truck and headed home it started rattling sounded almost like a diesel engine. I took it back and he adjusted the distributor said it was off a little. It ran fine for about 2 days then started making a lifter tap at idle then when driving it starts to make a louder thumping sound. I thought it might be a spun bearing but it doesnt make the deeper thumping unless the motor is under load while driving. I have been told it could be pre-ignition knock from being timed to fast. Could this be the cause or am I over looking something else it might be? Thanks in advance for any help I might get.