Recently, my 00 ES with 225,500 miles as seemed down on power a bit on acceleration and seems to have a surge, especially as I accelerate a little harder before shifting to next gear (5 speed). It idles smoothly, no audible misfires from tailpipe or during acceleration and no CEL. Any ideas as to what the cause is? Timing belt replaced as maintenance about 20,000 miles ago and newer coil pack, plugs, wires, and fresh 20w50 oil (has lower oil pressure due to miles). Passed smog very cleanly with low numbers across the board, so Im thinking ring seal is fine. Doesn't hardly use a quart of oil in 3000 miles.