Q: Car can't climb hills and doesn't accelerate well somethings when on level grounds

Hello, pls I own a opel tigra car. And the car struggles to climb hills and sometimes when I accelerate it doesn't change speed. My mechanic changed the plugs and and something called puller. But it still doesn't move well. Then there was a problem too with the crank bearings. I don't know if it's the crank bearings. I also changed the fuel pump and fuel injectors. My engine is not old, but i am getting frustrated so pls can I get help. Could it be the crank bearings.and what else could it be. It's ecotech engine. Tanx
My car has a manual transmission.