I have an intermittent electric problem...any advice would be very appreciated. The problem occurs very frequently, on and off constantly, but no pattern. The symptoms are an increased engine rpm, speedometer ceases to work, check engine light comes on, and fan will turn on when ignition is on (cool engine, not running). The car will run rough, and buck or stall. When the problem disappears, the car runs great. Computer code says ECM problem, replaced it along with ignition coils, same problem.