Re: 94 GT Problems
For what it's worth- it sounds as if your engine is not getting enough fuel. While you are correct that a plugged CAT can cause problems too, a plugged fuel filter, weak fuel pump, or bad fuel regulator can do the same.
A weak fuel pump or bad pressure regulator is easy to check with a fuel pressure gauge (about $15). And of course, the filter is the lowest cost part replacement if this has not already been done.
Save that expensive CAT replacement till last. I guess you could always drop them to see if it helps.