2000 chevy 3500 50-56psi fuel presure?

Question

hello my 2000 chevy 1 ton.only has 50-56 psi of fuel presure, will that cause hesitation under a load? like pulling a traylor or up hill? worse when the engine is up to running temp. it starts fine. it idols fine.it dosent smoke. i have done a tune up, replaced the fuel filter, and performed a leak down test on the fuel system. the fuel regulator seems fine acording to the leak down test.