sputtering at half throttle

hi there ,first off sorry if this is a repeat post. I have a 97 2.4 and im having issues with idling some times and when throttle is half open it acks like its gonna die. when I push the throttle to the floor it works beautiful , I have replaced the throttle position sensor and it work better then ever for 2 weeks then right back to it. in the mornings and when it sits for more then an hour it idles rough and will die if I don't push the throttle a bit. after I drive for 10-15 minutes it runs just fine no problems what so ever, please help me thank you.