After getting tranny issues and vandalized, today my ball joints went (again) and i'm hearing light knocking at idle. Two separate occasions this week, the car had a really tough time maintaining an idle but went away after revving and restarting the car. Today while parking i noticed that there is a light tapping/knocking that seems to correspond with the rough idle. The knocking goes away when i increase rpm but returns at idle. Any probable causes as to what is going on here? Seems to have happened after switching down from Premium to regular gas. I've done it a few occasions before but never had any problems like this. Thanks team.