Volvo Forums - Volvo Enthusiasts Forum - Tranny gets stuck in 3rd gear...Any idea?

So, I thought it was rough shifting but after driving on the highway today, I realized that 1st 2nd and 3rd gear are fine. It is when shifting into 4th(automatically or tip tronic) that it struggles. Once this "kick" or "pop" I feel happens, the car is stuck in 3rd gear. When exiting the highway, the car stays in 3rd, even as I continue to drive around town. When coming back on the highway, the car will not rev RPM wise any lower than 2,500, and likes to stay at around 3 thousand. When properly operating the car does 70mph at around 2,100 RPM. What is wrong here? When it does get stuck in 3rd, if I put it into Tip tronic, the car will not shift up or down. Just stays in 3rd. Hope someone can help....This does not happen 100% of the time, but is fairly often. 1st gears shifts to 2nd at around 10 MPH. 2nd to 3rd at around 20 MPH or so. Thanks