I have a 99 grand prix. I was driving about 73 mph. My traction control light came on and my rpm gauge drops to zero. When the car is restarted everything is fine for 15-20 miles the the same thing all over again. The car is at the dealer and showing no faulty codes for the crank position sensor. They replaced the ignition coil, wires plugs. I drove 3 blocks the same problem Any advice would be greatly appreciated ASAP.

Have the security system checked out but if the light isn't on for the system then whether or not the computer says anything about the CPS have it changed anyway. They can go bad and not throw a code. There have been a lot of problems posted by others on this forum that have led directly to the CPS and they didn't show lights either.