You need to a common event on the item that makes the timer appear and makes the character move faster. Then make a switch with that common event to another common event that has a conditional branch set when timer is 0-0 or less. Make it stop the timer and make the character speed back to normal.
Yea, no problem. Also you do not need the ME's or stuff like that and you change stuff around if you want. The ME's were there just to let me know that the item has wore off or has been activated.