1998 Forester stalling after starting and driving

My 1998 Forester is stalling after starting and while driving. It also bucks like it's running out of gas or going in and out of gear sometimes and may or may not stall when it does this AT Temp light flashes when this happens and some times check engine light comes on. Some times, especially when it's hot outside, it won't restart without a jump.(Battery and Alts. Been tested)Knock sensor has been replaced. The codes say it's the Mass Airflow Sensor, but a repair man put on on and said it made it run worse, so he removed it and just cleaned mine. Didn't help at all. I t's been put on a machine, but it still say Mass Air flow Sensor. Any advise or comments? Really need help!