What could it be
 

Just changed my oxygen sensors kinda late, my 2000 323ci has 141000 on it,:throwrock my check engine light came on even after I changed them the codes read oxygen sensor adaptation limit cyl #1-3 and #4-6 Motorized throttle valve(mdk) feedback plausibility and flywheel adaptation, segment timing faulty... yeeeaa any suggestions?:videogame

Most commonly its the catalysts - common problem with higher miles, and those other codes sound like a faulty Vanos unit