couldn't have said it much better myself
MAP Sensor (Manifold Absolute Pressure) Measures the air pressure in the intake manifold. Changes in engine operation and speed will affect the MAP sensor reading, which the computer uses in fuel and timing calculations. Often it will have a single vacuum line connection plus an electrical connection. Some turbo charged cars also use the MAP sensor to measure barometric pressure.
it'* no fun when they die. your car can't decide what it should be doing as far as fuel, so it'll cut it out, sometimes it'll dump it all in...
it'* a headache if it goes bad. luckily, it'* usually quite simple to replace on a car.