I have a 1998 Mercury Grand Marquis, which is my second Grand Marquis. I am very happy with it. I just had its first major cost since I bought it--it was maintained by an independent service station rather than the dealer. I bought two new front tires.
In 1968, I had a brand new Mustang Convertible. $2,400 complete, new. When I took it to the dealer for an oil change the price was $50, in 1968! I stopped payment on the the check, which is what I thought my lawyer was telling me to do. They reposessed the car from in front of my house. I sent an employee to recover the car with $50 in cash.
Since then, I have had a rule. Don't let an auto dealer near your car after you get it originally. I have been happy, and the auto dealer went out of business after I did a lot of publicity for him. (Not a wise idea in 2005--he would likely sue me.)
Complain to Ford and find a good mechanic. The late Mike Royko who was a wonderful columnist here in Chicago said that auto dealers view customers the same as butchers view cows, and the result is the same.