Today while on the highway i switched the altima into manual mode and shifted down to 3rd to pass a very slow moving car. It downshifted to 3rd and i floored the pedal. As it got to 3000 rpm it hesitated pretty bad for a few seconds but as it got to 3500 it picked right back up and everything was fine. I was able to get it to do it 2 more times under the same conditions and it did it again but after i let the car sit for a while it wouldnt act up again while I was on the freeway back home. The car has 173000 miles. Ive done all of my general maintenance. The only thing I havent done is plugs but was planning to here soon. The plugs look clean but the porcelain is a brownish maroon color. They havent been changed since about 92,000. The car runs solid otherwise in any condition. Im hoping it was a fluke....