First of all, (and I apologize if I'm insulting you) did you use the loosened expander to drive the wedge down? Quill stems don't loosen by simply loosening or removing the draw bolt. You have to physically drive the wedge down about 1/8" to free it.
If you have freed the wedge, my next step is to properly dolly the base (tire side) of the crown on a solid piece of wood in a vice or braced to the floor, and give the stem a solid blow to drive it INTO the steerer a bit. That often breaks any corrosive bond, and allows you to wick in light oil, and slowly work the stem free.
If all else fails I have vut off and reamed steerers with an adjustable blade, that's the hard way, and I reserve it for a last resort.
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