this is reading like a power supply issue .
take a thorough look at all wiring. there's a harnesss that runs up the front of the right side and breaks off to sensors and other necessities.its to the right of the oil fill cap. pull the insulation back and inspect the wires. sometimes the insulation on those wires can wear. clean bat terms and grounds. I believe there are 3 main grounds to check? even if positive cables from battery look good they can be corroded internally.