Used Mercury Cars for Sale near Newcastle, ON

My 2008 mercury mariner keeps dying on me anytime Im going over 50 or 60 miles an hour. Its starts chugging and jerkimg then all the lights come on I rapidly lose speed and power then I have to coast off the highway or road to pull over to the side but then it starts right back up again. I just had both manifolds and the catalytic converter changed and fixed and its still doing it. And someone said I have to get my mass air flow sensor cleaned off but im at my wits end with it. I just bough this car a week ago!