I had read that pushing the "tow/haul" button disables MDS. Otherwise you need a tuner like the Superchips to permanently disable.
There are also TSBs related to the MDS, maybe one will help you?
Here is a TSB related to the MDS for the 2009 models that sounds similar to your complaint
2008 WK "S" Limited bright metallic silver exterior, light graystone interior, 5 speed W5J400 transmission, June 18/2008 build, C213RE rear differential with 3.73 axle ratio, C200FE front differential with 3.73 axle ratio, 245/60R18 Goodyear Fortera tires (stock summer tires), NV245 transfer case, GT2056V turbo, 3.0L CRD (OM642.980)