Hi,
Yes fuel cell are soft and can be unstable, but they seem to work well for me in the New balance propel v4, no bottoming out - a great daily training shoe on a budget. Also you should try the new balance sc trainer v1 or 2. Every brand has some shoes that don't work for everybody. There are so many factors, how you strike (heel, mid fore forefoot), your paces, weight etc that can effect how a shoe can work for you..
Steve