2004 Olds Alero Stalling

Since early May 2009, I have been having a problem with my car stalling soon after the engine turns over. This happens occasionally.



I have had it stall once while driving and then it wouldn’t restart. The fuel pump was replaced and it worked for a while after that. Now it is acting up again.



Recently, the battery has also been replaced and the alternator was tested and was fine. A week ago, this happened and I took it into a mechanic. He looked it over and didn’t see any issues. He added an additive to the gas tank in case there was excess moisture in there.



But, not the car starts and dies. If I put it in gear immediately after starting and give it gas, it won’t die (at least not yet). Is there something that could be done to fix this problem? Or, do I have to live with it until it becomes a much bigger issue? And, what do you think the problem could be: fuel relay switch? ignition fuse? reset the computer? gas cap issue? loose wiring? oil pressure sensor? passlock key assembly? or others?

Just a clarification, this is actually a 2003 Olds Alero.