So I go to start my car yesterday and it was idling really rough / lean. I cleaned my MAF thinking it was that, but it wasn't. Also no CEL

So i start messing with some things with no success. I decide to just try and reset the ecu by disconnecting the ground.

Car started right up, no problem... What could have caused this issue?

EDIT - Forgot to mention this:

Also, the reason why i believed it to be the MAF Sensor was because when i unplugged it the car idled without stalling.... So weird