My 2000 Chevy Cavalier shifts fine before it warms up, but once it gets warm it feels like it occasionally gets stuck in neutral in between gears. You can hear (and see) the RPMs increasing, but the car doesn't go any faster, and then it shifts (sometimes fairly hard) and everything is okay from there. I was looking at the transmission fluid, and it was fairly worn out looking, not terrible, but for sure in need of a change. What are the odds that that is the problem? Details: 2.2L L4 Engine. 3 Speed Automatic Transmission 151,000 miles Last known tranny fluid change: around 98k miles.