I have an old, used FP .20 that will not peak out, but gets extremely hot and then starts to sag.

I am thinking that something is either bent, worn or warped. Do these symptoms suggest one or more of the following?

1. worn out bushing (the crankshaft has a lot of forward/backward play)
2. worn or bent connecting rod
3. warped liner or piston

It is not a fuel system problem; I'm running it on a test stand. The carb has been disassembled and cleaned and all engine bolts are tight.

Thanks, David