1999 d12 ecu problem

Truck has been doing fine until today, it almost feels like clogged fuel filter so I took both off ( both were clean) any ideas what to look for? This truck will hit a speed bump and just lose power!

 

No faults, runs great just lacks alot of hp it feels like it's governed when it hits any hill

 

It seems like at higher Rpm the truck just wants to give up. Also seems to be a delay in the acceleration at higher rpms

 

I don't know. Truck has a 10 speed and even when I'm empty I rarely can get to 10th gear

 

I was diiging around under the dash and found a harness connected to nothind and right next to it are two little black boxes the one was a dash control module the other i could not see but they are both connected and then their is this extra connector that looks like it was hooked to something at one time but its not anymore. their is also another opening for one of these modules could i be missing one of these module?