Car stalls and won't start afterwards

I drive a 2003 Corsa. It is giving me a lot of problems. It first started with it stalling, no matter how fast you were driving. It used to start again immediately if you turned the key again, but now it sometimes doesn't want to start. Then I have to wait for between 10 minutes and half an hour and then it starts up again. It also stalls when you start to brake. And it also feels like it loses power, even if you are still keeping your foot on the accelerator. And after it does that, it will stall. I have replaced the coil, I don't know what else to do.