Stock pressure is 39 psi. Surging is often because it's too rich, and that fuel pressure would make it run rich. My guess is the gauge is inaccurate if you have a stock regulator. I've run 340lph on stock rails and lines, the pressure was normal. It could also be a defective regulator. Harbor freight sells a cheap fuel pressure gauge you can use to verify pressure. I think most autoparts stores also rent them.