Ok. 1993 Nissan 4x4, 2.4cyl, 5 Speed. Truck will start and idle fine. You can drive it out of the driveway, and on flat roads fine. Once you start going up a hill it will start bucking and stalling. After it does it once it does it regardless of road conditions. Computer flashed a 55 (all clear). So, Im guessing its mechanical and not electrical. the only mechanical items in the fuel delivery are the filter and the pressure regulator. The filter has been replaced, but the regulator is $120 so I'd rather not buy one on a whim. Would the regulator cause this problem?