I have a 2001 Elantra gls which I bought a year ago. It had shifting problems from 2nd to 3rd gear with CEL on. I replaced the input and output speed sensors and connectors and fixed the problem to a point. It was still shifting a little hard even after a fluid change with SP111. I added 2 bottles of Lubegard red and it has helped immensely almost to the point of no problems....except. At slow speed shifting like going into a store parking lot or on a freeway with stop and go traffic, it will shift hard from 2nd to 3rd (I think) maybe 1st to 2nd not sure. If accelerating at normal speed shifts fine. No cel and the tranny fluid is on the full mark, not overfilled. Would a wheel speed senso cause this or damaged clutch pacs maybe?. Any thoughts or ideas would be appreciated. Thanks for your input in advance.