cold or wet outside issue

My 89 4.0 aw4 4x4 runs great until it gets cold or wet, particularly wet. At this point it runs horrible, like it has bad gas, stutters and backfires. I tried unplugging all the weather packs and cleaning with electronic cleaner and lubing with dielectric grease. any clues?

see if there is moisture in the distributor cap or the plug wires could be bad also