The problem with the temperature gauge could be one of two things. First, I would check the temperature compensation board. If you do a search on this website, you should find a tutorial that shows how to bypass this unecessary circuit. When the compensation board fails, it causes the gauge to give false readings. The other possibility, if the gauge is working properly, is that your themostat is stuck in the open position, which doesn't allow the engine to reach proper operating temperature. They are pretty easy and cheap to replace. As far at the power "bleeding off" I would check for a short or a bad ground wire. You don't tell us what year your car is, but some years, I think 85 through 87 had bad wiring harnesses that would disintegrate over time and cause all kinds of short circuits and problems. You can check your harnesses visually and see if the insulation on the visible wires is cracking, falling off, or missing. Replacement harnesses are available, or you can repair what you have.