We don't see any acceleration difference between our 01 and 03. The 03 is quieter with more tire/road noise in the 01, but that's irrelevant here.
Take a look at your manifold runner system, which Toyota calls "Acoustic Control Induction System." It sits on the top back of the engine, "back" in this case meaning at the firewall. It has a vacuum pot on it, a vacuum hose, a largish, hexagonal gasket, and an electric VSV vacuum valve at the other end of the vacuum tube. Any one of these components can fail. It might benefit from a very light touch of thin lubricant on the external mechanism. Thin oil is the key, sewing machine oil or CorrosionX if you have it. Not WD40 because it's mostly volatile solvent. You don't want dust build-up on the lube there.
My 02 Factory Service Manual also says to check the vacuum tank (under the battery tray)
