Hello all, I’m having some shifting problems with my 2000 Pontiac Grand Prix. I’m not sure what the transmission is, but I know the engine is a 3100. Anyways, the car seems to shudder when it gets around a certain number of RPM’s. For example, when driving in a 25 MPH zone and I try to maintain the RPM around 2100 to 2300 to accelerate, the car will at random times shudder. A few weeks ago the service engine light came on. After having it diagnosed at one of the local shops, the diagnosis read that it was the Torque Converter Clutch Selenoid Circuit Switch was stuck in the ON position. The mechanic pulled the pan and filter, showed them to me, and flushed the transmission. After he showed me the pan and filter, he assured me not to worry because the transmission seemed to not be shedding any metal. The mechanic told me the reason for flushing the transmission was because some of the valves in the tranny were sticking and causing the TCC Switch to stick. He added a transmission additive and explained the problem should work itself out. Well, a few weeks later the problems started up again and the Service Engine Light came on again during the middle of a long drive. After having the car diagnosed again at one of the local auto parts retailers, I received the same diagnosis. The Torque Converter Clutch Selenoid Circuit Switch stuck in the on position. Can anyone tell me what this switch is? How to get to it to change it out? Should I take the car to a transmission shop to have the tranny pulled and power flushed or manually cleaned? Help!!!