my muffins call for pastry flour all i have is all purpose flour, can i use the same amount

Yes. And I suspect you've got a lot of company. Simply take care not to overmix the batter. Pastry flour contains a lower protein amount than AP flour (around 9%, compared to 10-10.5%). The more you mix, the more gluten (protein) you develop, resulting in a tougher muffin.