94 s/c previa am2 fuse keeps blowing

i have a 94 toyo previa supercharged, and it seems when ever it rains, or the road is wet, i keep blowing the AM2 fuse thats located next to the battery with the fusable links. its a 20 amp fuse and when it blows, the van will turn over but wont start. its happened twice in the past week and its seems to fix itself after a couple days of sitting. i went through about 25 fuses tryin to figure out what was goin on, so finally just bought one of those self-reseting circuit breaker fuses. it died on me 2 days ago, and now it cranks up just fine. yesterday i unplugged the distributor and the coil and it still popped the fuse. i read throught a few post on here and someone said something about the distributor shorting out, so i disconnected it, and its still popping fuses. im at my wits end and dont know where to cheak next. any ideas???

update.. ok, so i've disconnected the coil, distributor, and all the fuel injectors... still poppin fuses. this would eliminate any of thoese components causing a short (unless its in the wiring). does anyone know if there is a relay for the ignition system for these vans??? and where it might be located???