96 Aurora Issues

I've had my 96 Aurora since 04 and absolutely love the car. One downside. It keeps stalling out.

Description of Problem:
Tachometer goes crazy
Speedometer goes crazy
lights on dash dim
eventually electrical power shuts down for a moment then comes back.
When stopped at a light or sign it jerks and the tachometer jumps


What I've had done:
replaced motor mount
OS sensor replaced
P/S Pressure line replaced
replaced plugs and wires
fuel filter replaced
radiator hose replaced
serpentine belt replaced
water pump belt replaced
I keep up with Oil changes
Throttle body has been cleaned

I've had the car into 4 different shops and none seem to be able to pin point the issue. The only sensor that is throw an error on my system is one of the Sensors attached to the AC unit.

I'm pretty much at my whits end as to what it could be. I don't want to get rid of the car, mainly because I can't afford another but I can't continue putting money into this one if every shop I take it too can't find out whats wrong with it.

Any Idea's what it could be would be most helpful.