97 GC v8 318 cuts out at 70mph

Intermittantly, around 70mph, the engine cuts out for a split second. The symptom is like a major buck. It is more prevelant when the AC is on. It does not do it under a load, just when cruising. I've delt with it for 3 years now... it is more of a nusiance. It may happen 4 or 5 times on a 100 mile trip or may not happen at all. New wires, plugs, cap+rotor didn't help... no error codes, tranny was rebuilt, new fuel pump... symptons not affected... still does it. Any clues as to what this might be?

Thanks
Charlie

2 things come to mind, CrankShaft Position Sensor or Throttle Position Sensor(altho I haven't seen a bad TPS cause bucking just a loss of power and throttle response). I have the test for each if u want to test them email me Joe dksob81@hotmail.com

The main thing that comes to mind is the fuel pump, but since you replaced it check the pressure at different rpms and see if it changes. CCould be ELECTRICAL CPS, Coil, CAM Sensor. Try to elimante before it leaves you stranded.