what could my problem be

Hello, well, it seems like you may have resolved the fuel delivery issue based on he fact that the vehicle starts and runs now. Based on your engine speed and stalling issue, it still sounds like a fuel / air / spark ratio issue. Too much or too little air, vacuum leak perhaps, throttle body concern -- something in that neighborhood. Also, emissions controls items can negatively influence operation and warrant investigation. It's all about testing. Good test equipment can monitor component function. This car is OBDII so there are methods to test that are successful. If you wish to seek assistance locally, here's a link to find a shop near you: www.repairpal.com/repair-shops