loss of control in rear

I have a 2006 double cab 4x4 with new shocks, and cooper at3's with about 30K on them. So far wear is good on the tires and are constantly rotated every 5k miles. recently the truck has been randomly fish tailing with little acceleration when driving. I've checked tire pressure, and talked with local mechanics but no one seems to know what the issue is. I was wondering if anyone else on here has had the same issue? i have 103K miles on the truck and this has just recently started happening within the last two months.

 

well i have always had that happen i dont consider it an issue but thats because im a drifter at heart haha but yeah it is kinda annoying when trying to drive in a straight line, but with and amount of force and nothing in the bed that end will come out