[jclark003]

If your grounds all check out look at the +vdc leads coming from the key switch. A poor connection there or a bad switch can cause voltage fluxuations resulting in the same symptoms. One easy check is to start the engines and run a jumper across the key switch battery and run terminals (not the start terminal). Just be aware that engine will not stop as long as jumper is in place. Battery usually has a red wire attached and is always energized and run typically has purple wires attached and is only energized when the switch is in the run position.