Runs out of power
 

I have a 2001 Mustang Gt. It has traction loc. I put 255/50/17 on the front & 285/40/17 on the rear. Now every once in a while. If you like go to get on the highway, it will top out at 55 mph and the traction loc light lights up. Even if you manually turn it off, it still does it. What is wrong with this thing? Thanks!