I tested your accelereation theory.
5th gear at 50 = slow. There just isn't good acceleration at low RPM in higher gears, even less w/ a high flow air filter.
Left foot to the floor, right hand down and back to the left, left foot out, and right foot down...
The only other thought, is ease into the accelerator, matting it at such a low rpm tends to bog the car for me... shrug.