This sounds to be an electrical issue. Start at the battery, clean all connections and apply some sort of corrosion inhibitor and be sure all connections are clean and tight. I use a product from the electrical trade called No-Alux which you can get at Home Depot. Brush on the clean and tight battery terminals. Check the ground strap at the ECU, clean, protect from corrosion and make sure it's tight. Hope this helps and good luck.