I have a 1997 Ford Mercury Cougar, it has had problems for the past year I'd say. One issue is taking corners, not all times but sometimes the rear left side of the car will have a thumping sound in around 1 second intervals for the time taking the turn. Then the other problem is the engine, it's had it's engine light on for almost a year. I've taken it to get fixed 2 times, since then it stays fine for about 5 days then it returns. The average gas mileage is supposed to be 27 MPG but lately it seems less than 20, it has trouble picking up speed on the highway for quite a while. It will take sometimes between 1-3 minutes to get past 65 but after that it's smooth sailing. The shop says it's something to do with the fuel line, they fix it then it comes back within a few days.
Any help would be greatly appreciated, thank you!