My dash is showing a slow down or shift up i have an 06 xc90 ocean breeze racing edition v8 awd automatic with manual shift option but trying to figure out what sensor it is and where its located and how hard is it to change without sending to closest dealership 250 miles away

 

Your first step would be to scan the car with a compatible scanner to see what self diagnostic codes are stored. Then use that and other related observations/information to formulate a diagnostic plan. There's not "a sensor" that's causing the problem. A sensor is simply reporting a problem to one of the control units.