Just to amuse myself, I ran one more tank. I tried every setting from stumbling rich to wavering/rattling/clanking lean and everything in between.

It will not maintain a constant rpm at any needle setting and pinching the fuel line sometimes speeds it up and sometimes slows it down- at the same needle setting, whether it's rich or lean. It is hardly producing any power regardless of the needle setting, and it shakes and rattles like it wants to explode. It makes the strangest noises of any 2-cycle engine I own - like it's banging itself to death.

Even though I can't feel any play in the rod, it's acting like the rod bushing are worn out. maybe the play gets worse when it heats up.