thanks for the response! so, a clogged cat was my first thought when all this began. when i originally investigated, i found an exhaust manifold stud was broken, manifold probably warped, and also part of the exhaust connector busted, and so i replaced the entire system from the manifold to after the cat with a donor from the 1995 mighty max donor vehicle. that vehicle had been working fine, no signs of bogging, though was burning oil (and had a busted leaf spring).

again, what seems weird to me about this is that it's able to rev up when i feather it (ie. just barely open the throttle), but WOT bogs it badly. similarly, it actually accelerates briefly whenever i let *off* the throttle, like something is being released. based on the carbon deposits on the plugs, i've assumed this means that when the throttle is opened the mix is getting super-fuel-rich, but i'm not sure why that would be.

i'm also wondering about spark and the ignition system. though the distributor cap looks newish, i'm going to try swapping it and seeing what happens. really appreciate all the ideas, keep them coming!