I need help getting my 2001 750iL running properly. It gets a steady or flashing check engine light when driving. When idling in gear it is very rough. Definitely missing. I used my Bavarian Autosport scanner and it reported misfire on cylinders 1 through 6. I replaced the cap rotor and plugs. Now I get a random misfire and catalyst damaging misfire on cylinder 2. It seems to be isolated to cylinder 2. I removed the spark plug wire and then the wire for injector 2. There did not seem to be a change in how the engine ran. I also replaced the ignition wire for plug 2, no change was seen. The problem also seem to be isolated to the 1 - 6 bank of cylinders. I removed the coil plug for banks 1 - 6 and the engine rpm was low but it was smooth. When I pulled the coil plug for 7 -12 the engine barely ran, was extremely rough. In the end should I replace just one injector or replace all 12? I see a few places selling used or rebuilt injectors that have been flow tested. Also I changed the driver side OSV 2 weeks before as it was making a hissing noise.