You wrote front, right? Virtually any Shimano brake/shift lever will do. Well, be a little careful with double vs. single -- the lowest-end Soras must be matched, but at least some of the the higher-end models (at least 105 and some above, iirc) will shift either a double or a triple as-is.
You probably covered this, but make sure that you don't/didn't have a cable which was fraying at some point, either within the shifter or somewhere farther down the line. This can make shifting all screwy before the cable breaks.
Also make sure that the front derailleur is unobstructed and free to move.
Good luck!
-Greg