my car has been giving me the same problems, I have been through 5 alterantors in a little over a year, first off make sure that you have the little bracket on the back of the alternator bolted up good, I found in my case that not having that bracket results in vibration at high rpms and that was causing the rear fan in the alternaor to come apart and short out the stator, next look very closely at you power dist. center under the hood, mine got water in it and that caused corrosion and also shorted out intermitenly causing my starter to engage while drivinf down the road. even after pulling the key out it would still crank. next I there is a power and ground wire right next to each other, ground goes to the bell housing, power to the starter, mine rubbed together and would intermitently short. What I have finally ended up with on my car after many trails, is this solution. I replaced all my main power and ground cables with 0 gauge amp wire, including the wire from the alt. to the mega fuse and from there to the starter and battery, also I too have a system and one thing many people fale to realize is that the ground side of the electrical system must carry the same current as the power side. I see lots of people run 0 gauge pwer wire and 8 gauge ground wire, they need to match. long I know but I dont want you to have to go through all the trouble I did, oh and do you have a capacitor? might think about one, or the one of the new Advanced Glass Mat Batteries. I have seen them do amazing things on cars with systems. good luck
