will partially disconnected exaust just ahead of an oxygen sensor cause poor performance?
Yes air gets in and causes a misreading. Is your check engine lit on?
yes,on and flashing
Don’t drive it w/ the light flashing until the issue is fixed - and don’t assume that the only issue is an exhaust leak.
Yes, a partially disconnected exhaust system just ahead of the oxygen sensor will lead to poor performance of both the engine and the driver. Have this repaired right away in order for both to function properly.