FIRST OFF check the connection ive seen the connector come loose if you have a strut tower brace running across the top of your engine bay. when the engine moves from the load on it. blah blah it can hit the bar and pop the connector off.
you CAN test the map sensor but you need a multimeter. it has 3 wires going to it. 1 of them is ground. 1 of them is a power wire which MUST HAVE 5 volts sitting at the sensor. the other wire is the signal back to the computer. the simplest way to explain how it works is the computer sends 5 volts to it. depending on your engine load it sends an amount of voltage back to the computer, lets say 4.5 volts. and it calculates the difference and recognizes how much of a load is on your engine.
you should ahve about 2-2.5 volts on teh signal wire at idle and at wide open throttle (WOT) it should be anywhere from 4.5-5 volts (but it hardly ever sends exactly 5 volts back to the computer because there is some voltage drop inside the sensor due to resistance.)
just use a multimeter, set it to DC volts, turn the key on, engine off. and see which wire at the connector has 5 volts at it. plug the connector in, start the engine., back probe the wires with a paper clip and one wire will have no volts at it the other should have roughly 2.5 volts. (if its working) then give the throttle valve a snap to WOT and you should see the voltage go up on your multimeter.
if you get no voltage change BUT you have a 5 volt reference at the one wire, your map is bad.
but if you do not even have 5volts on one wire then it depends how compitent you are with wiring. cause now youve either got a problem with the computer. or a broken wire.
sorry i cant remember what colour is what, but you can still figure out what wire does what by what ive told you!
if you dont have a fucking clue about what i just typed. thats why this world has mechanics!
good luck!