'94 Z34 power windows are intermittent.
I found a wiring weak spot last weekend in my '94 Lumina that might also apply to some of the other W's out there so I thought I'd share what I found. The wiring harness from the drivers door where it enters the body (interior side just above kick panel) turns down and rubs against an unprotected sheet metal edge. The factory didn't bother to wrap some of that plastic tubing around the wires in that area. After 160k miles of vibration it finally wore through. The window circuit breaker would get fire hot with the key on. Amazing it didn't start a fire. I fixed it by slipping a 3" piece of vacuum tubing slit lengthwise over the metal edge (passenger side too), but you could also wrap the wire. Windows work great ALL the time now!