99 Alero Stalling

Hi all. I have a 99 Alero with the 2.4 and auto trans. It has been a great car but just in the last week, had a problem. While my husband was driving to work, it stalled as he slowed to get off the freeway. He stuck it in neutral and it started right back up. It did it again yesterday. Today he left it with me and it tried to stall as i took off from a stop. Then it tried to stall when i slowed to turn into a parking lot. Each time it did stall it started right back up. COuld this be a fuel filter or something more? No lights have came on to indicate anything on the dash. Thanks for the help.

A bad altanator could cause this. have the alt checked out and the batt. as well. If that checked out, fuel filter,plugs,wires and pcv valve. put some dry gas in there to, could be little water in the tank.

I'm having the same problem. Every morning I drive across an airport tunnel and my 99 Alero V6 automatic always seems to stall or feels like it's about to stall when I reach the last 1/4 of the tunnel. When it does this all the lights on the dash light up like a christmas tree, the door chime goes off, and they all turn off and I only see the security light solid for a moment and then it starts blinking. Then everything either goes back to normal or it stalls. I don't have to do the whole 10 minute procedure thing even if the security light is blinking because after it stalls, I can start it up by turning the car off and starting it again right away and get where I need to go. Funny thing is I pass the same tunnel again going home and it never happens. And it never happens anywhere else I go. Only in the morning and only in the last 1/4 of the tunnel. Pretty strange. I need to fix this because I could seriously get rear ended in the tunnel. I got it scanned for free at Autozone and it showed no codes. My guess is that some signal in the tunnel or when the light sensor turns the headlights on, it is causing the electronics to screw up. Any ideas on how to fix this?

In this case, bad altanater will cause this to happn. replace the batt and the alt. Usually its one light at a time. I have seen this many time, this is how i came othis conclusion(sp).

I got the alternator and battery checked out at Autozone and they are ok. I think what's happening is the bumps in the tunnel are causing the ignition cylinder sensor to send out sporadic readings of the key resistance and that's confusing the BCM on whether to activate passlock to disable the fuel injectors or not. That would explain the intermittent stalling at the same spot. But wouldn't this just cause the security light just to light up signaling that there is something wrong with the passlock system and not cause a stall because I think the key resistance sensor signal is only needed at startup, right? Does this all sound plausible?

The passlock is not supposed to shut the car off once it is running. A "wrong key" signal while the car is running will turn on the security light, but will not shut the fuel off.
Passlock has two modes. One is "fail-disable", and is activated when the wrong key is used in a start attempt. The other is "fail-enable" and occurs when the wrong key is detected and the engine is already running. The BCM considers this to be a passlock system fault, not a theft attempt, and will not shut down the car. It will turn on the security light, however.