V12 throttle actuator failures
ALL the Bosch electronic throttle actuators have defective insulation on the wires in their wiring harness. If the engine does not pull strongly to redline, but starts hesitating and making weird sounds around 4-5000 rpms. suspect the throttle actuator wiring harnesses (integral with the actuator) on the driver side. It fails first. First check out a second mortgage. These are over $2400 each. Send me your old ones and I will rewire them.
Not sure how many years the problem covers but it is from early 90's through 96 for certain. Also many of the other wiring harnesses in the cars have the same defective iwiring insulation. The stuff turns to crumbs continues to work until the harness flexes. Then intermitent failures and shorts.