That doesn't sound bad at all. Have you double checked pick-up inside the tank for restriction or crimping? Is the pump fairly new? I have run into a couple of the red pumps losing their vane clearances inside and bypass the fuel when they run long. Armature and winding amperage getting too high from heat or wear causing a slower action. Without being hands on with this project, it's hard to give a good diagnosis. I'm only throwing ideas out there for now. Be patient for a little bit, I know somebody here has also experienced this and figured it out.