Cruise Control problems of the 2007 Mercury Montego

Multiple instances of my car accelerating while in a lower rpm such as at a stop light, drive thru window and parking lots. Especially increased instances when the air conditioning is running. This also causes the car to die completely in some cases. I have to try to pull over somewhere in order to put the car in park and restart it. This issue with the acceleration is increasing in frequency lately. I can count on it to happen every single time I have the air conditioner running and sometimes when it is not. Problem has occurred hundreds of times. It is very dangerous! if I were slow to react to the acceleration, the car would definitely run over a pedestrian or hit another vehicle! local Ford dealership vehicle was purchased from said they were not aware of any issue like this occurring in other like models. Please help! last night my husband and I went through a local restaurant drive thru window and while going through the line, the engine surged 5 different times! these are not slight little rpm bumps, these are full fledged "the car thinks I am mashing down on the gas pedal to obtain speeds of like 45 mph" accelerations! today I was driving at around 35 mph with the air conditioner on and turned the cruise control on. The car died when it reached a downhill turn at the point I would have expected the cruise control to hold back the speed. Of course the power steering went out when the engine died, so I had to try and find a place to "float" into in order to turn my car off and restart it. I need this fixed very badly before my family and I are in an accident. I cannot afford to spend thousands of dollars at the dealership hoping they get the correct diagnosis nor can I afford a new car.