FIrst, I agree, I don't think that is the right fluid.
Second, You dont mash the throttle and breaks. You need to jack up the rear of the truck, chock the fronts GOOD, and put the truck in drive. at idle, I believe you need to manually move the TV lever to full forward and monitor line pressure rise and total pressure. Let us know what you wind up with. There are ways of adjusting it if need be.