load the game, online or off, goto the stick cal screen. In the upper blue box are some lines that move when you move the stick. With your stick at rest, all the lines shpould be strait across with out any "blips" in them. If it is bouncing around like a heart monitor hooked to a guy watchin "Jessica Simpson" videos, your stick is a mess!!
Recal the stick, then got to each axis and sliding the "dead band" slide up a bit at a time try to get rid of the spikes.
If the lines are strait from the start, it maybe a driver issue. As you said MS doesn't support their sticks any more, but "Google" it and ya might find some aftermarket type drivers.