I have a 1995 Chevy

I have a 1995 Chevy Lumina which is in good shape. Last August the cruise control module went haywire. When I go around corners or up small hills, the module overcompesates and then cuts out, i.e., I am going 55, and when I reach a slight incline the module jumps to 70 and then disengages. Same with corners. Once it starts going haywire, it is no longer smooth on a straight flat terrain, i.e., it quickly goes on and off, herky jerky down the road. Since this time, my service station has put four modules on the car, and they all do the same thing. He has thoroughly checked the car out, but can't find anything wrong with it. Is there a bad batch of AC Delco cruise control modules out there?