99 a4 1.8t with many codes, running rough, no boost. need help!

[99audiA4quattro]

Im new to this form and to the audi scene. i bought a 99 A4 quattro 5speed from a friend because it needed some work. when i got the car the car was idling weird. it would drop and increase in rpms. it also seems like the turbo isnt boosting up. the car is not running under full power. i took it to the shop and they pulled these codes from the car. P0102: mass air flow ckt low p0501: vehicle speed sensor range performance P1128: long term fuel trim multi bank 1 system lean P1300: random misfire detected on one or more cyl P1602: power supply terminal 30 voltage low p1555: change pressure maximum limit exceeded I have been doing alot of research on what these codes are and what could be the problem. since getting the car i put a new battery in it and also replaced the mass air flow sensor and checked all fuses and replaced the bad ones. I noticed that the Crankcase Breather hose is broken would this cause all these problems or is it other things as well? please let me know what i need to do/check. I just wan the car to run right again before i put it on the road. thanks for your help

[Prospeeder]

well a broken breather is an air leak. And air leak makes it lean. Also air leaks are somtimes boost leaks. ALso being lean enough causes missfires, so yes, fix the breather