Check the ground wires, normally corrosive, or broken
Balance it and then check kinpins play...
I both cases, just check it all , i mean all
My father has 59 years old, and has 8 trucks running; house, car, etc. he will never retire until, he feels it is the time...
your tach sensor need to be checked, also check cables, and at last your tachometer
you are expecting too much, thats ALL, when you want to use fridge and such things, only when truck is running
