2012 WESTERNSTAR DD15 hesitation

Ohhh k well there was a few codes in this truck like low oil psi and coolant level, excessive coolant temp! And ITV BRIDGE 1 circuit! Went for a test drive not one code came up, kept laptop hooked up lights would flash and not sure what it met…. Truck is deleted.

But what was happening is when the truck reached 1650rpm truck would jerk and red stop light and orange light flashed on dash, told him to keep foot on pedal and truck would keep jerking, until he went under 1600rpm lights would stop flashing. Anyone have any experience with this?

 

What it turned out to be was a blown engine lol. CPC was not storing codes to read and head gasket was leaking. Took it to auction as what bosses orders were