Fuel lag
 

My 98 Cummins is acting really sluggish. It runs fine starts normal but when I push the peddle driving down the road the fuel peddle is firm and it dosent get up and go any more. It use to roll the coal but now when I mash it it don't do any thing. Any ideas?

What is done to the truxk? Rolling coal doesn't particularly scream horse power. But it sort of sounds like you may have a fuel pressure issue. Due to a failing Lp or ofv. But there are other symptoms of thay aswell.

check the signal line going to your AFC make sure its not leaking or broken. That is where I would start followed by the shutdown solenoid. Most likely one of these two things is your problem