Another WTS question
 

Ive read several posts on here about the WTS light, but they usually have some upgrades done. I have an 06 3500 that is stock, except for the staight pipe. My WTS comes on when I let off the accelerator after a hard uphill or long pull. It doesn't matter if empty or with a 12k pound trailer. Also have noticed decreased MPG, and now it is idleing real rough. Been going on for a while. Any ideas? Thanks in advance.