Vacuum leak

I've had a vacuum leak on this car since I bought it . I finally found it's on the back of the motor if you're standing in front of the car back of the motor to the left, so it's not very good explanation of where, but got a sensor going to it. I think it's just the seal I don't know the name of the part. I've tried to find engine bay schematic that show in the part but still can't find out the name of this part. I guess I will send the image of it with this.