Engine misfiring on all cylinder
 

Hey i just brought my first BMW a couple of weeks ago. I'm having a couple of problems with the engine. The guy that i brought it from claimed to be fuel related but i recently i had it scanned and here are the codes.
P0300
P0301
P0201
P0202
P0203
P0303
P0304
Now i know most of these codes are related to the misfires and injectors, but the guy said he replaced all the injectors and spark plugs. So i'm kinda in a pickle right now. The engine does seem to struggle when it tries to go up a hill. But im really looking forward to fixing her up. Thanks for the help! Forgot to say it is a 1997 318ti with the m44 1.9L

Probably vacuum leak.