My first thought after reading the title was fuel issues. Could be a plugged screen in the tank. I would suggest biocide to verify good fuel....also fuel and air filters if you have not done that yet.

As far as a compression test not being decisive I disagree.

I also predict your compression test will show this engine is mechanically sound.

Good luck!

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.