[Razorback1980]

The sending unit cannot cause the starter to malfunction. The starter has nothing to do with a temperature gauge except they both draw current and current starts at the four ends of the battery cables and is distributed through the starter solenoid where the battery cable attaches to the solenoid. Try attaching the negative side of the jumper cables from the battery ground to the engine block and then I would also attach the positive side of the jumper cables to replace the positive battery cable. I'm thinking one of these two actions will fix the problem. If this fixes the problem take off one cable at a time to see when the problems return to figure out which cable is losing connectivity. The whole car draws the current through these cables which is why you are having problems throughout the car.

Tom