spruce goose

Having same problem, '92 SC 300. Mine has gone so far that on freeway, overdrive cut off and windows wouldn't go up. Have a new battery. Independant mechanic says not alternator or battery cables. Not using lighter at time of loss of power. Bought car new. Had had major oil leak problem when I brought car here to Texas found Dealership to be pretty clueless and expensive. Friend of mine who had worked on car figured out problem before they did, so let's hope someone can help threw posting.