2.9 runs poorly, can't figure it out

[88rangerxlt2.9]

Need help, 88 ranger with a 2.9 spuders, backfires, timing advances and has no power once it's warm. Runs somewhat okay when cold. Has me totally stumped. Truck sat for five years so I replaced both fuel pumps and the filter. Replaced coil, plugs, wires, cap, rotor, adjusted timing (set at 10° off tdc). Replaced the MAP sensor, cleaned throttle body and intake. I'm fairly confident I'm not dealing with a head gasket issue and have checked for vacuum leaks, can't find any bad wiring. I'm very unfamiliar with electrical/sensor issues and have a sneaking suspicion that's what I'm dealing with as it also will randomly decide to run like a dream for a day and the next it's right back to the usual crap of running like shit. Also is 10x worse if it's raining. Anybody have any good leads of how to diagnose or what I could be before I start taking shots in the dark. It seems to me reading these forums many of these faulty sensors seem to give similar symptoms.