94 GS Down on power in every gear

I have a 94 GS, 1.8, 5-sp that is down on power. Every gear is the same. The car fires right up, no engine light, just no power. I am not sure whether to start. It seems maybe the cat could be clogged...but I have read that injectors and ECUs are common problems.
The car revs smoothly but slowly, with no hesitation or jerkiness. It just takes a while to get up to speed. Usually at around 4000 RPMs the car tends to pick up a little better. Also, it loses power going up hills.
Anyone seen this?
Cats?, Injectors?, ECU?, etc