Hello, I drive a 1999 5.7 L 4x4 Automatic LT Tahoe with roughly 242000 miles on it. I just replaced the engine in December due to a cracked gasket, but now I'm having an issue which I think is related to the transmission. In January, shortly after the engine was replaced, I was driving it back from California to Arizona. Once I got into Arizona and was driving in between 75-80, I would feel a kind of kick, as if the transmission was trying to change gears or something. This only seems to happen when I'm between 75-80 and it is still happening to this day. I have no idea what it could be. There are no leaks or anything from the car. Could it be that the tranny is going out? I mean, it is the original tranny as far as I know(I bought the Tahoe used last summer), so it would make sense that at around 242000 miles it would have some issues. Has anyone had a problem similar to this or knows anything about these transmissions and could provide some input?