1996 Z28, its starting hard and the SES light is on. OBD Scanner says "Left Bank Lean" when I add fuel cleaner, the light goes off for a short while. Then it comes back. Does anybody have the diagnostic chart for this condition? Or know how to fix it?

 

"left bank lean "........that sounds like it could a worn out o2 sensor. have you ever replace them before ?

 

or a vac leak.........

 

Or a misfire on that side, plugged injector(s) on that side, exhaust leak before the O2 sensor on that side...... and the list goes on.