1999 Jeep Cherokee Runs rough, no power

This Jeep Grand Cherokee is driven often but not daily. It was running fine when parked and then a week or so later when started it ran very rough and has not enough power to move when in gear. It does idle rough and stays running but not running good. When accelerator pushed the engine will rev somewhat but poorly. Also when reved the dash acts funny, ie. The lighted digital odometer goes blank. Also, the volt gauge shows no movement but there is charging voltage at battery. I have also discovered resently that the electric cooling fan does not run(overheated while at long idle with ac on) but the fan will run when battery voltage put to the fan directly. Are all these electical things related?