Jim,
I have one of those too. I suggest you drop the exhaust pipe at the manifold and make sure you don't lose the little doughnut that is usually in that flange. Then start it up and see how it runs. That will answer your possibility of an exhaust system constriction. If this doesn't get it running its time to pull both the intake and exhaust manifold and see what may be in one of those intake or exhaust passages. It sure sounds like there is blockage up near the engine block in an exhaust port with the heat description you give.
Normbc9