I have noticed that some days my car pulls better than other days. Then on some days the acceleration just seems kind of "mushy" I guess. Just wondering why my car seems to perform better on certain days.......... maybe its just psychological.

Thanks

maybe it's the weather

Yeah seriously, it could be the weather. Humidity, smog level and temperature can all play a part in engine performance.

Ambient temp and general heat soak of the engine induction components.