Hi everyone, I always feel that my car has slower acceleration time (0-60) then a lot of you guys did on the forum....I replaced my MAF about 2 months ago then dis/reconnect the battery, feels much quicker but only last for about 2 weeks then it gets slower again. I tried to do the reset ECU thing and doesnt feel quicker. Last week the check engine light came on and mechanic saids is the O2 sensor problem. I didn't replace it yet and I just dis/reconnect the battery and clear the light. The car is back to quick again. So if I replace the O2 sensor will the car be quick like right after I disconnect and reconnect the battery all the time without dis/reconnect battery every like 2 weeks? or is there some other reason that the car only gives the quick performace after dis/reconnecting battery? Is a 2000 E55 with 110000km on the car now.....no mods except for the x-pipe. Thanks!