Bluesbelly

I im new to this forum. I recently picked up a tdi a4 s reg for little money which was in excellent nick aoart from a cracked winscreen. However when i tested on the open roads it did nt accelerate and had trouble going up hills and reacging 60 mph even on the motoway. People in the know said i should change the air mass sensor which i did for the cost of £56. The difference was astounding. Now it accelerates performs well and has power. Is there anything else i can do to fine tune it to further improve it. Also the mpg seems exceptionally good. Is this right