The transmission is probably slipping. It's possible the transmission bands may need to be adjusted though, so you should take it to a mechanic to be sure.
you need to have the bands adjusted.
why is my manual transmission slipping on my 1999 chev cavalier
No. A slipping transmission is caused by a low fluid level, or failure of friction parts inside the transmission. Though a failing Vehicle Speed Sensor(VSS) can cause symptoms that can make it appear that the transmission is slipping, even though it is not.
my 1990 mercury marquis transmission is slipping in overdrive what do i need to look for and how can i fix it
Changing your transmission filter will help in improving the slipping under load.
The Bands in the transmission are slipping/ the tranny is bad.
It could be a bad clutch.
A slipping transmission on a 2002 Mitsubishi can be caused by low fluid levels. Check the fluid should be the first step in troubleshooting the issue.
my son bought a 1996 cougar that felt like the transmition was slipping and we had the transmission flushed and it fixed it.
sorry but there is no belts for the transmission! if it's slipping it's most likely a clutch or band problem if it's the bands some can be adjusted from the outsid ebut should be done by a professional! if it's the clutches you have to remove and disassemble the transmission and have them replaced!
Motor or transmission mounts. That or your transmission is slipping one way or the other.