hi guys, I have a 2008 chevy impala 3.9 police interceptor. I checked at advanced auto and it didn't show an error code. the transmission hesitates whenever i try to shift gears. On the highway between 50-60 mph,the RPM goes to between 4-5 and it feels like the 3rd gear doesn't shift into the 4th. It also feels like the car has minor heat up. I talked to a few people, they said the transmission clutch is blown or maybe i need a new transmission. The thing is it only hesitates whenever I go uphill. What can the problem be? if anybody can help, i would greatly appreciate it guys, since the transmission is very expensive.