Fuel pressure
 

I have a 96 12v (details in sig), my problem is when I'm towing my enclosed trailer and I start up a incline on the interstate, I apply a little more pedal to maintain the speed but it doesn't want to pick up anymore...
It acts like there is no more pedal after half throttle or less...
I carried it to Swamps Diesel Performance in Nashville TN (they done the mods to it) and they said its low on fuel pressure...
Said it has around 7-9psi at idle and 16-18.5psi at WOT...
I know this is low...
They recommended replacing the lift pump with a Air Dog electric pump...
My main question is, is this what I need to do and what size pump?
They offer a 100, 150, 165, and 200 I think...
Open to any suggestions...
I want it fixed right, this truck is used for towing only...
Will be doing other upgrades eventually...
Thanks for the help...

Most Popular Fuel System Troubleshooting Flowchart:

Step 1) Does the truck have an AD/FASS/Raptor: Yes: Go to step2
No: Install AD/FASS/Raptor

Step 2) Does the truck run right? Yes: Finished
No: Needs a new AD/FASS/Raptor

Step 3) Not a fuel system problem