BMW Repair: 540i sluggish w/ check engine, mass air flow meter, mass air flow

Question
Evan,
Background: 2000 540i w/ 95K miles, check engine light is on and is sluggish especially when cold. I have had it in the shop and had lot of things checked.  Codes indicated mixture rich on right side.  Tech thought O2 sensor should be OK (since no codes).  It did have leaking valve cover gaskets which where replaced and coils checked out OK, replaced plug boots, did a smoke check which was negative.  Tech swapped injectors left to right but I never went back as I moved out of state.  Tech suggested next step was to look for new codes and replace injectors if error moved sides.  By the way it also had a sever hesitation at 3500-4000 rpm but spraying :a special" cleaner on the air mass meter fixed that right up...
Several questions:
1) I would like to be able to diagnose this but I only have a simple code reader which doesn't allow for detailed info.  Is there a code reader you can suggest which will give detailed info? Will I be able to use it on other cars like my wife's Acura? Mucho dinaro?
2) Should I pursue the injector replacement or do you think it could be O2 sensors?
Thanks!

Answer
Mike, injectors from my experience have rarely been the cause of a mixture too rich condition in BMW's. Your spark plugs and O2 sensors should be replace at the 100K interval. The most common issue with mixture too rich fault is a faulty Mass Air Flow meter. The meter reads too much air, the DME adds the fuel and ends up getting a too rich reading from the 02 sensors because the air mass was not as high the airflow reading. The DME then trims back fuel and you can see hesitation. Make sure your air filter is not restricted. There is also newer software for you DME to avoid erroneous check engine lights and O2 faults being stored. Scan tools are exactly what you pay for, but I myself am considering buying a system that you can run off your desktop/laptop computer. So If you are really into diagnosis then swap O2 sensors side to side. I think they should be replaced soon anyway though. Look at those plugs too. That will tell you if one bank is running rich. Most probable cause is MAF meter. Please fill out a follow up survey if this helps.
-Evan