My truck was acting very strange on the way home from work today. Me and Semper just changed the transmission fluid and the U joints in my Bronco. I have an 87 with a 302 and AOD. Now, it is acting very different. When I press the accelerator it makes a very deep and steady noise. I can feel it through the gas pedal. It seems to do it whenever I accelerate or am trying to maintain the same speed while going up a hill. Anyone know what this could be???