Roscoe52

My 1998 R129 SL500 is not adjusting the fuel/air mix at altitude. At sea level (where I live) it runs nice and strong, instant power with a tap of the throttle, but when I get up in the mountainous states (from 2,000ft on up to 10,000ft) power drops off and fuel consumption increases, which seems (to me at least) to indicate the fuel/air mix is not compensating for the lower air density at altitude and the engine is running rich. Here I am talking about level running around, say, 8,000ft, not climbing, so comparable running to sea level just up higher.

I have replaced the O2 sensors but the problem persists. I have a persistent pending (not current) error code of P0130 - sensor 1 bank 1, which has been replaced twice to date one year apart. I can't believe that the car is eating that sensor every year.

No other error codes, never had a CEL. HELP!