ok guys today i notice that when shifting from 2-3 or 3-4 that theres is a little vibration and a little stutter nothing real bad but i can feel it. so when it happens i let off the gas and it stops. it only happens when im going real slow through the gears. if im going about 3000 through the gears it never happens, and it doesnt happen ever time. what would be the best thing to do about this?