I had the stalls as well, and they went away after replacing the battery. I’m pretty sure that there is no way to fix your phone with software. It’s a hardware

I had the stalls as well, and they went away after replacing the battery. I’m pretty sure that there is no way to fix your phone with software. It’s a hardware problem. Just replace the battery, and it’ll work fine again. I don’t know where you live in Crete, but typing “iphone repair cityname” in google should quickly get you to a place that can replace your battery in 15min.