I've only owned the car for 2 years and there has been no problems other than just the last couple days the cooling fan sticking and therefore some overheating before I caught it.
I purchased the car in Alberta and on returning to BC the inspection revealed a looses tie rod which cold be classified as routine.
My main complaint with the 1998 year is listed below.
I owned a 1995 (from new) before this car and even at 290,000 kms the 1995 was smoother, quieter and just a bit more of a pizzazzey ride. The 1995 obtained NOTICEABLY better fuel mileage also - both on highway and in the city.
I am a bit disappointed in the 1998 because of the above and on a minor point it lacks a few little things that made the 1995 base model a bit more "luxuroius. The 1995 had two - 12 volt power points while the 1998 has one. The sunvisors in the 1995 had two parts and had more class/style than the 1998 does.
Just all round if another buyer could find a 1995 with te same mileage he was getting a 1998 for in my opinion he or she would be getting a better car. The 1995 was virtually trouble fre the total 290,000 kms I owned it.
You mark your review for a 1997 model, not a 1998 which it sounds like you have. As far as the gas mileage goes the 1995 model has better mileage due to its more aerodynamic look, the 1998+ has a blockier look (?). I had a 1992 Grand Marquis and have since upgraded to a 2000 Grand Marquis.