I have been reading the problem that one man had with the vent? I am confused. If you remove the vent and the water goes out with no problem and does not back up even through the open pipe why would the drain be clogged?

I have the problem with the vent on the water backs up in both sinks. With the vent off it runs fine. I have tried three different vents and still no success.

So you are saying that this sink was not vented via a vent stack to the roof, right? You are using a Studior brand AAV for your sink drain vent. Where is your Studor mounted and is this a new installation?

This is a new sink installation and you are correct it is not vented to the outside it is a manufactured home. The new sink was a little deeper and we thought this was the problem so I raised the vent as high as I could behind the sink but does not help the problem. After reading the solution to another gentleman saying the line may have a blockage I have decided to go under the house and cut the line and put a cleanout on the end and try flushing it out with a hose. I installed the line and it is easy to get to so I should be able to do this. I will respond back if this was the problem and solves the problem.

If you installed a deeper sink your trap may be draining at a level too low in the cabinet to match well with the pipe coming out of the wall, the studors should be mounted to that pipe by the way. How did you go about raising the AAV, it should be on a horizontal drain pipe.

It was directly behind the new sink on the pipe coming out of the wall and goes straight up behind my new sink. The only change I made was to attach the two pipes to my new sinks when I installed the new one.

Is the tail piece coming out of the sink above the pipe coming out of the wall?

Yes it is

OK I am about out of ideas because this should vent. If it drains with the vent removed but not when the vent is in place then the vent (AAV) in this case is bad. However you won't find 3 bad vents in a row. There is some detail we are missing. I'll keep thinking.

Can you take some clear pics of aav vent location and post them here?