Cummins N14 still having problems

Guy's i'm about set this truck on fire!!!!
1995 International 9400 with N14 in it. I bought the truck about a year ago,truck ran good bobtail,i bought it in Sioux Falls,SD and drove it to Houston,TX no problem. When i hooked it up to a 53ft trailer it still ran good. Once i got the load onto the trailer, it was a different story! The truck almost stall's taking off,if you catch a light on the incline,110% the truck will stall when you try to take off. Only way to take off without stalling the truck is to rev up to 1700rpm's and dump the clutch. It will stall sometimes even by taking off like that. I've been to 6 different shops trying to fix this problem and it never got fixed. I'm gonna list what was done to it. Took it to the shop to see what's wrong and was told that it needs new injectors,ok go ahead replace them. New injectors put in same crap happening. Need new turbo,ok go ahead replace it. New turbocharger and problem still there. Took it to another shop and was told that it needs an inframe. Ok do the inframe! So they did inframe on it and guess what?same crap! Took it to another shop and was told ok i see the problem,you need a new ecm!ok let's get the new ecm. New ecm and new ecm harness put on and nothing has changed,truck still runing the same no changes. Took it to another shop to try my luck,they changed all my fuel lines (and i mean all of them) put on a new fuel pump aswell,same thing,the problem is still there. I got tired of shops so i did some work and testing myself. I replaced the charge air cooler,all the engine sensors,wire harness for sensors,cleaned all grounds,did the fuel bucket test,new starter,new alternator,new clutch,new transmission,new sensor that goes under the accelerator pedal, all this crap and nothing has changed since the day i bought the truck! I even took it to cummins and paid $1200 for diagnostic and to update my ecm,there is no check engine,no codes at all. Cummins said truck runs good,i know it runs good bobtail! I don't know what to do with this truck,i'm about to pull my hair out!

 

500hp 1750tq it came with 9speed eaton fuller and i swapped it for a 10 speed eaton fuller. I dont know the ratio of the transmission but the rear end is 373. I always take off in 1st gear.

 

It was the same with 9 speed,it would stall unless you rev it up. Also my fuel milage is always 4.6 4.8, no matter how i drive the truck. It's driving me crazy. My brother has a 96 9400 with 525 celect plus and it pulls hard and gets 6+ mpg,he's truck is a 9 speed aswell.

 

Yes,i replaced all battery cables and cables that run from batteries to the starter. I also ran cables straight to ecm to see if it helps.

 

I replaced the sensor on the pedal but not the pedal. I live in Houston,TX and i run TX to MT and back to TX every week. Exhaust is new from turbo all the way back.