Car stalls while idling also acts like it's going to stall in between 45-60 mph

We have had the car a few months and for the past month it has been dying while the car comes to a stop or is idling. It will start right back up most time but there has been a few time where it would take 3 or 4 tries to get the car started. Also while driving in between 45-60mph the car will jerk or bog down like it's going to die. We have taken it to 2 mechanics $400 in "repairs" later the car is no better and still doing the same thing. They cleaned the MAF, throttle body and a few more sensors but nothing has worked. PLEASE help, we are at our wits end with this car already!