I have a 2007 Lincoln MKX that I purchased new. I've always changed the oil and had maintenance and updates on it when due. I'm had numerous problems with it (headlamp harness has caught fire, had to replace the transfer case) but lately it's been chugging at 40-45 mph and sounds like you are running over rumble strips (like the ones on the side of the highway). I've had it in the shop for this exact problem but of course it wouldn't make the sounds or chugging when the mechanics drove it. When put on the machine - no codes appear. It's getting worse & I'm afraid it's going to leave me stranded. I've read one other complaint that points to the Drivetrain. Has anyone else experienced this? If so - what was the problem & how much was the fix?