well my car isn't stock, but I was trying to accelerate from different speeds in 5th gear. Starting at 50 slightly uphill seems to be no problem at all. Elevation I'm sure is different here and I do have Borla header which does give some extra torque. One thing is you don't want to floor it at a low RPM in a higher gear, just ease into it.. fastest drivers are very smooth... I would definately change your fuel filter. To me that sounds like the mostly likely cause at this point.