I have what sounds like a similar issue with my 95 - it will occasionally bog like you're describing, but it's only for a few seconds after it's completely warmed up and when it's really hot outside. I'm thinking it's a heat soak issue with an ignition component (coil or ignition module) but it's very intermittent and impossible to duplicate it for diagnostic work, so the problem remains.

If your trans cooler lines feel warm then you should have good fluid circulation, but it won't hurt to check anyway. I'm not sure which line is the return - maybe the FSM will have that info. If it ends up being an internal transmission problem, I'd recommend finding a good used one in a wrecking yard rather than trying to have yours rebuilt. I've not heard of anyone who's had good luck with a transmission shop rebuilding one of these - they almost never break so most shops have no experience with them.

Unless your engine has extremely high miles on it or poor compression numbers there should be no reason to rebuild it. I've got 255K miles on the untouched bottom end of mine, and the only reason the heads came off was to replace the leaking valve stem seals (common Mitsu problem) at 120K miles. Other than doing the timing belt and associated parts as maintenance, the valve stem seals and the variable intake butterflies are the only common problems to this engine.