2006 Mustang GT automatic 36000 miles. Only mods are CAI, Axle backs, and the worlds best tune. The tune included changing the shift firmness of the trans. All was great till today. I took the car to a friend of a friends oil change service. They changed the oil and filter, were told not to check other fluids. It is one where you drive in and they go downstairs to drain instead of on a lift. The guy said my car was done. I stood there the whole time. I get in the car and drive away. My friend follows me in his 2011 5.0, who also just got his oil changed at the same place, same time. We decide to run em. I always pull him by at least 2 cars. This time he pulled me by a half car, and I noticed the trans didnt shift like normal. No firmness at all. He even noticed that it didn't break loose in 2nd. Not thinking anything about it I took the car back to my wife. (she loves it) When she got home the first thing she said was "why doesn't the car shift hard anymore"? I called my tuner and he said he doesnt think it has anything to do with the tune, and I went to call the shop that did it but they were closed. What would cause this? I am hoping that it is low fluid or something. Any thoughts would be great. Sorry for the novel on my first post.