Air mass sensor for E320
 

I have two 99 E320s. one with 110,000 and another with 30,000 miles.
The one with 110,000 has had the air mass sensor replaced 3 times.
I just replaced it again and it went out after about 2 weeks. The trouble
code is P0136 and P0141. Any idea what's eating these things? Or is
it maybe not the air mass sensor and something else giving this code?

Sounds like you have a defective oxygen ( O2 ) sensor.
http://202tech.mkosonen.com/howto/enginecodes2.html
Btw. it is the one AFTER the catalytic converter.