lbw

I have a 2010 Mercury Mariner, base model. Three days after I took delivery in 2010 it died while I was driving it and wouldn't restart. Dealer gave me a new battery and the next day I had a "brown out" (slow down) and took it back and they drove it and it died again, so they figured out it was a loose wire going to the electrical box. All was fine. Then about a year or so ago, I turned into a driveway and it stalled as I was still moving, and the dealer couldn't find anything.
(Meanwhile, I had to get the tranny overhauled after only a year, but that's another story. This car is shite.)
So I was driving about 25mph a week ago and first the radio turned off and then the car just slowed down. I was able to coast over to the side and turned it off. When I turned it off, the car shuddered a few times. Turned the key and it grinded for a second or two and then started. I was able to drive it to work and made the dealer come down and get it. They have now had it for FIVE DAYS and can't find anything. They keep driving it in an attempt to replicate the problem, which of course is not happening. They said they checked alternator, battery, throttle something or other and a lot of other things. So far they aren't finding anything.
Any ideas?? And what if they can't find anything? I do not want to drive this car ever again.

tomw

Poor connection at the battery cables or the other end, starter relay and/or body ground.

I had a similar 'slow death' in my Ranger, and it turned out to be a loose connection on the battery. Radio quit, dash lights went, started to run poorly, barely made it up a hill, died at the peak, and coasted into a gas station. I was able to turn the cable on the battery post, and after tightening, everything went back to normal.
tom