My car has been acting up lately too. Ever since I reset the ECU and had to have my car set up with the airbox mod, it has never been the same. However, in your case I think it is hard to pinpoint a cause.
For instance, the weather has been changing in my neck of the woods. It was averaging in the mid-30's when I first bought the car, and now it is up in the 50's--70's. As the temperature goes up, density altitude increases (which is the altitude at which your car will perform.) This change can be very dramatic. Additionally, tires tend to grip better in warmer temps.
I also noticed in my car that the clutch isn't as grabby as it was when it was brand new. It was almost annoying initially because it was difficult to get a smooth engagement.
Perhaps there are several factors to consider.
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2001 SE, P/P, 5 spd. Cloud White.
MODS:
- Stromung Stainless Cat-back.
- Ghetto airbox...Zip ties and all!
"I always wanted to be somebody, but I should have been more specific."
For instance, the weather has been changing in my neck of the woods. It was averaging in the mid-30's when I first bought the car, and now it is up in the 50's--70's. As the temperature goes up, density altitude increases (which is the altitude at which your car will perform.) This change can be very dramatic. Additionally, tires tend to grip better in warmer temps.
I also noticed in my car that the clutch isn't as grabby as it was when it was brand new. It was almost annoying initially because it was difficult to get a smooth engagement.
Perhaps there are several factors to consider.
------------------
2001 SE, P/P, 5 spd. Cloud White.
MODS:
- Stromung Stainless Cat-back.
- Ghetto airbox...Zip ties and all!
"I always wanted to be somebody, but I should have been more specific."
Just an advice .That's why I replaced the stock one see my mods.I feel the same as you as the time passes. 
