What do i need to do?

Well I'll be honest with you.. I just thought you were trolling with that kind of a question and attachment of a car

Having said that, torque is what gives you power to climb a steep hill and you have 1850 lbs which is plenty but your problem is gear ratio its too fast so you lose lots of momentum shifting gears. You need to change gear ratio to at least 3.73 if not slower. It can be pretty expensive to swap only you can figure if its worth it

Sorry if I came across as an a hole but it was just weird to see someone asking how to go faster than 85 mph and not being familiar to thing such as HP vs torque vs gear ratio after driving for 9 years as you claim

 

just bump up RPM or top speed setting up to 2000 or 1900rpm and you will have 10 or 15 more on speedo keeping CDL will take more. does truck still have power when you are running at 1500 rpm;

 

If you really really want to run faster buy your self a Bully Dog reprogramer and run as fast as you want.

 

Get rid of that big red boat anchor and get a CAT.

 

umm, ... are you governed or speed/rpm limited!?