When i am in 3, 4, 5, 6 gear at a certain rpms my car will spike the rpms u and then drop them back down when it catches back up with itself. i don`t know what it could be. In the fuel as in fuel pump or with the air intake or a crank positioning sensor. anything could help.

 

Does the spike correspond to changes in speed? Or is the speed constant and the RPMs still spike?

Also would be helpful to know year and transmission.

 

sounds like you have a 6spd. If you are going say 40mph and get on the gas to the RPM's suddenly rise or do they stay steady and gradually increase? If the first, prob your clutch. The TL has a self adjusting clutch so you won't know until it's gone that it is really gone.