I was having this exact problem. Tried everything, even got a new phone. But when the new phone died I dug the old a13 out and accidentally figured out that for some reason the ghost touch problem goes away when the phone is charging. No idea why. Probably not good for the battery to constantly be plugged in. And it's certainly not convenient during times where I'm not near a charger. But as an immediate solution until I can get a better phone plugging it in solves the problem.