Car Forums - car problem

i have a serious problem with my car, it's a 1991 toyota camry prominent auto transmission, 4vz-fe engine. After getting a under carriage i realised that the engine started to race, the rpm gauge went up well above the 2 on the gauge and would'nt come down i take it to a mechanic and he turn down the throttle but nothing change. then he go as far as opening the airflow sensor on top of the airflow pipe and mess arround with it then the car start to shut off each time he starts it. he re-ajust it and it went back to the high rpm, i was told that it is a computer problem that water get into a sensor, could this be? i am a novice to motor vechile i wouldn't know, so if any one out the with the knowledge of these cars i am asking greatly for your support, thank you.