My transmission has only done this 3 or 4 times, but it has me worried. If I deccellerate and then accellerate again (i. e. coming off the freeway, or slowing in traffic) it shudders, almost like a clutch chatter. I have it in overdrive when this happens. Today when it did it, it seemed like it had not down-shifted and should have and thats when it shuddered. The only things done to the truck since this started are the 275's and a switch to mobil one transmission fluid.