Lost of power on 2006 vnl 670 cummings isx

Morning drivers, am in need of help with 05 vnl 670.i was driving and suddenly lost power on my truck.when i give it fuel its not accelerating and its only going 20 mph.i dropped the trailer and put my blinkers on and went to a fleet pride store and bought a new fuel filter.after the new filter i took off and truck was driving normal for like 3 miles then the same problem came back.truck is idling ok and reving ok when idling but once i start to move its a disaster.please help me.thanks in advsnce and there are no any fault lights on my dash.

 

I think the problem is my pedal.its giving me code mid 128 pid 91 fm 12

 

Incase you ever expiririence loss of power and the truck will not accelerate like the problem i had above,you might end up having a problem with your throttle position senser.after a long day trying to figure out what was going on with my truck,i lifted up the pedal and the dash was filled with all kind of STOP ECU.after i changed the whole pedal and sensor myself,the truck is driving like brand new right from the shop.dont get ripped of to have anyone change that sensor cuz its an easy job.just two nits and unplug the sensor and throw in the new one.

 

I have alot of knowledge with this truck.i always get help from this forum and saved me thousands of geting ripped by dealer