[70Stub]

89 k1500 with the 5.7, auto trans. Truck runs fine down the road. Set the cruise and it starts sputtering, misses. Take it off and truck runs fine again. Has new plugs, wires, rotor, cap. Nothing else has been worked on. Cruise did work fine but now I can't even use it. I ran a separate ground to it thinking maybe that was the issue. Any ideas what is causing this? Thanks