This has never happened for the entire time I've owned the car but it's done this twice within the past week and I don't know what type of problem this is exactly.

When I start the car, it will die almost instantly unless I give it throttle, and every time I drive and stopped at the lights or something, the car would die and I would have to start it again and keep my foot on the accelerator pedal to let it not die. I pulled over, waited a few minutes and then the car ran normally. I looked at the battery and it's fine (the green light thingy) and the voltage needle goes down from where it's normally until the car dies, other than that it's usually good.

All I can think of that I've done differently is possibly the sound system when I installed a new sub and amp but even then it did it once before I installed the new ones.

What's the possible cause for this exactly?

have u disconnected the battery for a period of time

Moisture trapped under the hood with all that rain I reckon. had the same problem with the BA if parked outside in the wet for 3 or 4 days without using it. when it rains constantly it creates a lot of condensation which gets trapped under the hood when the sun evaporates the moisture off the ground in between downpours.

Sounds like a lack of fuel pressure. Does it do it cold or hot? If hot could be the oxy sensor also

Battery hasn't been disconnected for a while now, but I have tightened the nuts to the + - terminals just to make sure it was nothing loose.

Hasn't rained around here for days now, if so it hasn't been heavy.

I think it has been warm/hot days when it's had the problems, not sure how old the oxy sensor is, only had it since I got extractors fitted which was about over a month ago now.

Forgot to mention that I had been driving for about an hour and a half, stopped the car for about half an hour, loaded the car up with stuff, then it had the problem until I was able to pull over and check the engine bay.