Psp problem

A few months ago my psp started controlling weird. When I play a game like madden, it was hard picking plays cause it would jump side to side and when trying to move right the guy would move in slow motion. I tried joysens to center the stick and didn't work. I found out when I start the game over it would get better and work fine till around halftime then start getting crazy again. I have to older non workin psps so I decided to switch the analog out and the dpad. Now it moves worse. So I switched everything into another psp that I just messed with for parts. I replaced the stick and the dpad and fired up madden and it acted the same way as my other one. So I took out the dpad totally and left the analog and it still jumped around. So I replaced the dpad and removed analog entirelly and same thing. I don't get it