Transmission Problems

Hey,
Yesterday I replaced the Upper Torque Bushing on a 98 Volvo S70 and many of the problems were cured...i.e., hard shifting, delayed engagement after hard braking, etc. However, we still have a problem shifting from third to fourth gear up steep hills. The tach will go up to 3.5 grand before it cycles between 3.5-4-3.5-4 and then finally engaging into fourth. Sometimes it cycles even more and in larger intervals (3.5-4.5, etc.) A new transmission was put in under warranty after it was purchased by an Acura dealership. Would the problem be a software issue after the new transmission was put in?? Any input into possible problem areas would be helpful. Thanks.