1999 430 ml.check engine light on and off
 

OK, I ran the codes at the Autozone, and I bought 2 O2 sensors from the mercedes shop, and installed them, I also replaced the brake light switch for the other light on the dash, but both lights keep coming on. It seems that when I have a full tank of super, with the gas cap on tight, my check engine light goes out, and I have a lot of quick power and acceleration, when my fuel gets lower or the day is hotter, here in phoenix, the engine light comes on again, and I loose the engine power...got any ideas? My engine runs real well if my check engine light is off! thx, mike:cool: