'00 "garage lurch" need help PLEASE!!

00 lesabre limited "garage lurch". was told it's the automatic transmission pressure control solenoid. This is for my parents, who are being told by the dealer that "it's a very expensive problem", however, on MSN, i see that the part is roughly $25.00 with roughly $250.00 for labor, based on a flat rate of $65.00/hr. WHERE is this part located on the vehicle? is this something that someone can do on their own?? Just trying to help my folks from being taken advantage of, while mom's car is currently at the dealership!!

Any and all help is greatly appreciated!!!

If this is the confirmed problem, which should be scanned with a trans capable scanner to confirm, the PWM solenoid is internal.