cauz i don't have the file i'll probably cover stuff that u'v already done or tried. with that said...
1. are u sure that the textfield was not scaled or streched with the transform tool.
2. (mx only)have u turned on the View>Snap to Pixels feature? with this feature turned on u can zoom in on the text to view the grid that the font sould fit exactly in for it to be crisp.
3. are u sure that the font will fit with in the pixel grid. meaning not all pixel fonts have the correct spacing and will fall off the grid if the textfield is large (i.e. the line spacing or charater spacing will start falling outside the grid).
4. are u sure that the font size is correct for being able to fit in the grid?
5. did u open the info pallet and change the black dot on the bounding box to the upper left. the upper left corner is the one that should be set to whole numbers.
6. i found that even using whole numbers, some fonts (like a few from fontsforflash.com) don't exactly line up on the grid so u have to tweek the x or y a decimal point over to make it work right.
hope one of these tips will help and sorry for covering stuff u probably already know.