depending on which injection system your 5.0 came equiped with, you can gain a little extra bottom end torque by adding a larger throttle body.... takes a matter of minutes to change out... computer wise, you're really not going to push that much further than you have.... the AOD, if you're gonna keep it, 100k is pushing it on one of those gnarley beasts..... add some redline transmission fluid to it and take care of it.... it'll make it shift a little better, and if you're lucky make it last longer.... preferably converting it to a manual isn't going to be that big of a deal, and if you really want to keep it for being a "classic" someday.... keep the AOD in the garage for some later day