1993 Lexus LS 400 what the-my car is evil

Electrical problem
1993 Lexus LS 400 V8 Two Wheel Drive Automatic

purchased used few months ago. Dash lights up for while then goes out. Same with fuel gauge. The last owner told me about this and said that some module in the dash is bad and cost more than he is willing to spend. All the problems stil exists. The new problem is when the car idles down to stop light etc the automatic air changes sometimes colder sometimes to just fan. A couple weeks ago it left my wife stranded and I had to jump start it. I purchased a new battery even thought it didnt look old. Now the alternator will not charge the battery. I pulled the records the owner gave me and was shocked. The alternator has been change every year an half since 2004. The battery was replaced for the second time 2yrs ago. I looked at the alternator and it looks brand new. Is this common for the lexus? What could it be that is causing problems to the alternator and electrical system. When the dash lights go out the speed dial drops to zero thank goodness for tom tom. If you have heard of this or have a educated thought let me know. Also every time the lady had the car serviced she had the electrical checked. One shop that she stopped using made special note about the alternator has been checked for two straight days.