2000 Q45 intermittently dies immediately after start

[NateB29]

So my 2000 Q45, 167k mi, has this intermittent problem where it dies immediately after it starts, unless i give it some gas then it will rev up and start idling normally. This only happens about once every about 5-10 times i start it. After doing some searching it sounds like it could be a vacuum leak or my iacv, but this problem only started happening after i left my lights on at work and drained my battery. I had to get a jump to drive it back to my house (20 min away). So is it possible I damaged my alternator and/or my battery by doing that? I am going to go to autozone tomorrow if they are open and have them test both, but I am trying to get a good idea of what i will be looking at in terms of replacing or repairing parts. thanks in advance

[NateB29]

update; had the alternator and battery tested, battery was bad, alternator is good. replaced the battery hope, i'll see if this continues, hopefully not

[NateB29]

ok, so after 4 days from replacing the battery, it did it once again. started it up and it died right away. started it again and had to give it gas to keep it alive. So it has a new battery. autozone says the alternator is good. what else could it be? idle air control valve? vacuum leak? fuel pump or filter? maybe the mass air flow sensor? could it be my alternator is on its way out but autozone's test did not pick it up? There are no check engine lights on, can i diagnose any of these without replacing each part?

[goody90q45]

I'm not sure about the 00Q45 but in the 90-96 Q with the same symptoms and no CEL it points to the fuel pump controller going bad. There's a couple of recent threads that show a picture of how to bypass the FPCU so you might try unplugging yours and see if the connector has the same pin orientation and try the jumper bypass.

[NateB29]

So im not sure if this is related to this intermittent problem, but yesterday my CEL actually came on and I was able to pull the codes today. They came back as a knock sensor in bank 2 (p0330) and and o2 sensor in bank 2 (p0155). Is it likely both of these are out or is a more likely scenario my harness is faulty? Or would it be best to replace both sensors (o2 and knock) and see if that does the trick? BTW my car is running great aside from this dying when starting thing... its not sluggish or hesitant at all