2012 kw t660 issues

[FSCOTT1520]

i have just taken delivery on a new to me t660 with a def cummins engine with 450k miles on it. while it was at the dealer it kept having issues as if it were running out of fuel. no throttle pedal, skipping, sputtering, etc so i kept making them try to fix it. well after a month they had supposedly gone thru the fuel system, checked pressures and all was clean and well, then they thought the turbo was bad so put on a new turbo then finally it gave a code on the test drive and they discovered the egr valve was stuck and the egr cooler was leaking. replaced both of them. did a forced regen and then checked the flow pressure and it was .5 so the filter was definitely clean and no exhaust flow problems. i took delivery then on the 29th. truck has been from atlanta to dallas to elpaso back to atlanta over to chattanooga out to stockton, ca and back to baton rouge, la. driver has appt to unload in pensacola in the morning and goes out gets in the truck and drives 2 miles and hits a bump in the road and the truck starts skipping and sputtering again. he cut it off for about 15 minutes and now it is going down the road just fine. i am thinking an electrical issue such as loose connection or broke computer wire somewhere. it doesn't give any codes at all when it acts up. any and all ideas ya'll have would be greatly appreciated. thanks