240sxxs

ok my car is 1997 240sx kouki front end.. with KA24DE-T is have around 87,070 mile on it..and the car was originate set up for albercurky( however you wanna spell it ) New mexico, Now is in tempe ARIZONA. and New mexico is 1 mile higher then tempe Chandler where i live.. i bought the car as is. now ill drive the car with the owner and the car start up fine but when u drive the car , the car get hot and then when u put back in neutral is idle slow and then stuttering then die, and the owner keep pressing the clutch and then it stuttering and then stuttering then it die even he release the clutch and he in neutral.. but if u give it a little bit of gas then it good. but if you not in gear and in neutral and just park there such as stop sign or red light it die out . the wierd thing is when u turn the car and start it back on ..and then it idle fine. i ask the owner what happen to iy and he said that is MAFS ( Mass Air Flow Sensor ) but im not sure if is it..i really like the car and i already have cash in hand and ready to buy this car but just want to ask fellow s14 owner what could possibly happen or anyone in the same siuation before.