So while driving my truck last night on the highway I noticed that at 40-45 and 70-75 the truck would shake violently from the front end but once it was no longer at those speeds or not accelerating at those speeds it would go away. I mainly felt it through the steering wheel and the floor. My tires haven't been balanced for a long time nor rotated because it isn't worth the money with old tires I plan to replace soon. Also in an unrelated statement my truck for some reason just was not down shifting when it needed to last night it just kept in 4th when I needed it to be in 3rd to get up a hill. Finally is it normal for the truck to up shift when you release the gas and get back on it? - - - Updated - - - Really still no one has an answer?