So i have a 2007 MCS with about 52000 miles on it. My problem is this, when i am accelerating my car has plenty of torque or pull up unitl about 2500 rpms and above. then it feels like its not pulling as hard. its still speeding up and the rpms are still increasing but they are not doing it with the same pull that it usually has. when i shift to the next gear it continues to do it. it seems to only have torque befor 2500 rpms. Any ideas what could be causing this?

 

Carbon build up.

 

Touque*