2006 Dodge Caravan gages and lights going crazy

I bought this car a 16 months ageo and have had this problem for 13 months. Ive replace the alternator twice checked the battery and battery cable. My mechanic is at a loss he has check the ground bolt . Now the car will stall out while Im driving with no warning. It will go for awhile without the lights and gages going crazy until I use the AC or radio or headlights then the lights go nuts. I need help this car is driving me nuts.. Thanks