well a TPS not functioning right will certainly cause a sputter or low power.
Does it work fine forward up a hill? I'm thinking perhaps the engine torquing is causing something to short out. Had a Toyota that the Crank Sensor wire was shorting against the power steering line, but only in reverse when you backed up fast (or up a hill). It would stall, but immediately restart.
'91 Frankenheep YJ. 4.0, 4" BDS, Richmond 8.8, Titan 12k, 35" KM2's, rust.
'88 YJ, 4.2/4.0 head, +4½" & shackles, BFG 33's (sold)