Bad brakes
 

I did a cummins repower and solid axle swap in a 97 1 ton and tore all the factory abs proportioning stuff out of it and put an adjustable proportioning valve in it. I took the truck for its first drive the other day and the went to test the brakes and found they will stop the truck eventually. When it's not moving and I run it through the gears it holds it there but when it's rolling with any momentum it won't even come close to locking the brakes up no matter where I adjust the valve. I think it's the valve I bought and my buddy thinks I need to go with an old school brake booster that isn't hydro boost. I'm going to contact the company about the valve tomorrow but figured it wouldn't hurt to get a second opinion.
Any help is appreciated
Thanks, John