Stalling Subaru

My Subaru want to stall when it shifts from a higher to a lower gear when driving up a grade/hill. Also does the same thing when pulling out from a stop sign or traffic light. You need to pump the accelerator to get it going. Kinda’ like me when I get tired!

At what point do you plan on mentioning the certain needed facts. like year, mileage, and how long has the check engine light been on and if it is blinking?