I'm not sure if it will be worth buying for $150? It runs and drive but its super loud knocking/clunking noise can this be a spun rod bearing any tips and tricks to diagnose myself would be grateful thanks

 

Depending on the year, unplug the coolant temp sensor which will throw it into open loop (no computer control) .If you can ground each plug wire one at a time, if it is a rod brg it will lessen the knock when you hit the right cyl.

You will get multiple codes from the computer, just remove the negative battery cable for 15 min , depending on the year, and the computer should reset.