I would do a charging system voltage drop test first. I would also see if the charging system is putting out the right amout of amps at the right voltage just to start and check the voltage regulator switching voltage. The voltage drop test of the charging system will tell you if you have a bad connection somewhere. If you dont know how to check all that maybe you have a buddy who can do it. Or you may have to pay the tech to check it out but make sure you get a tech who knows what he is doing. Sometimes a problem like this is tuff to fix over the internet and calls for a hands on look at it. Good luck , Ron