Isuzu Rodeo - Possible Electrical Problem

I think my Isuzu Rodeo has an electrical problem. Sometimes it will not start. Sometimes it will lose 90% power while driving. I haven't noticed any patterns in regards to when these problems occur. I've taken it to several mechanics (not Isuzu dealerships) and all of them have scratched their heads about it. It has not been driven regularly for the past year, since I've been traveling, however, I have had someone take it out every now and then to keep the battery from completely discharging.