Sometimes you need a fresh set of eyes on a problem like that. Do you know any engine builders who will take a look at the engine with you? Sounds like you're missing a bunch of power so it has to be something fairly big. It could be the convertor or the trans too. Those things can kill your ET if they go bad. Heck, one time I lost a bunch of power because my emergency brake got partially locked up. Took me a while to figure that one out!