Hello guys, we have a problem. We have a hesitation during acceleration and it seems that our air mass meter doesn't work. The gas milage got worse too. We've been in the BMW dealership on the computer, and it proved it. Don't know what to do right now

. People said to him that it's gonna be around $300 to replace the whole thing. Could you give me any suggestions, diagnosis.....

'98 bmw 328i w/sports package.