Iphone 4 touch sensor issues

So basically I just changed the digitizer and glass screen on my iphone 4 for the second time, few days in great update it fine till today the thing goes absolutly spastic at times and starts 'ghost touching'. Locking it then reusing it works but only for a few minutes, when I type a message g and t are unable to be pressed it thinks i'm pressing letters next to it.

Funny thing is as soon as I plug the phone into power(apple charger) its fine and has no issues :S Thinking maybe faulty digitizer or something?