the prefilter still has fuel in it (with a small bubble). It doesn't really matter if Im going uphill or not, but it does seem to make it happen earlier if Im having to start from a full stop and accelerate or accelerate more to go up hill. I did completely replace the fuel lines (the rubber any way, not the steel) except for the lines I just discovered in the spare tire bay leading to the small (reserve?) tank that is behind the spare. There is evidence of some fuel leakge there. Plan on replacing those this weekend. I haven't messed with the fuel cap or vent, but will give that a shot. thanks!