transmission "hunting"

ok guys..been a while since ive actually posted a thread. my truck has started acting strange when slowing down and coming to a stop at speeds less than 40 mph. its almost like the accel pedal is being pushed 2 or 3 times in sequence when im completely off of it coming to a stop..opposed to the normal immediate down shift in to 4 when letting off. I changed my rear end gear oil to syn about 4 months ago. the trans doesn't slip and shifts fine. the fluid hasn't been changed since purchase but I have checked it and the color is good and doesn't smell burnt. the truck has a 140k on it. could this be a throttle position sensor issue or does it sound more severe?