1999 Buick Century Q&A

1999 Buick Century Question: price for codes, fuel filter replacement

Having trouble going uphill, and generally losing engine power. Thought might be transmission, plugs/wires, fuel pump. Mechanic charged me 80 for code reading. Fuel filter replacement $42. Total $141 and still don't know what is wrong. Overcharged? -
Answer 1
What codes did he retrieve? -