The company that Moar Performance Sells or Tengis is the same way.
I have sold quite a few pumps and only a handful of people have this problem. I also have them installed in my three wbodies... no hard starts here. It could be the check valve in the pump. I always install the hoses with the supplied clamps and such. If you believe the problem to be the hose on top, you can actually replace the plastic currogated fuel hose with a submersible rubber hose that will undoubtedly seal instead.

...then told me I need to rewire the pump too. F that. Sell a good product.
If you are running the pump without a fuel pump rewire then you are doing yourself a disservice. These pumps are a vane-impeller design that pulls more amperage over a gerator style pump like stock or a Walbro 255. They NEED to be rewired to function at their best with full voltage going to them.

When I install these pumps I drill a hole in the top of the fuel pump canister and run the wires from the pump pigtail out of the hole. I run a 12 gauge wire from the battery to the trunk feeding a relay that is activated by the stock wiring. I also connect the pump ground to the stock harness and add an EXTRA ground that is mounted to bare metal in the trunk somewhere or underneath the car.