For starters its illegal to take out the cat converter. Many people hollow out theirs but to me the $10,000 fine if you get caught isnt worth it. Just do the usual:
exhaust, extractors, intake mods (you dont really need a pod, a replacement K&N panel filter works just as good), possibly a cam. Then you get into the head work!
You could try a diff upgrade...a set of 3.7 or 3.9 gears should get it launching quite nicely!
(I6's only have one head, not heads :))
Dodgey ideling can be caused by many things - plugs / leads / dizzy cap / rotor button / ISC / TPS..the list goes on and on.
It all comes down to how fast do you wanna spend!!!
Good luck with the ea...i want pics