Shifting between 3rd and 4th while maintaining constant speed
 

I have a 2004 allroad with tiptronic. I am getting ready to change the tranny fluid. I have noticed recently that while maintaining a constant speed the transmission will shift from 3rd to 4th to 3rd and continue doing this unless i go faster or slower. So usually around 45 mph. The shifting is smooth when this happens.

Well I am now thinking this is more of a surging issue. It is also happening in tiptronic in 3rd and 4th gears.

A VCDS scan would be helpful.

No codes were thrown for this problem I don't believe. I have a bad secondary airpump right now and a p0421. So the VCDS scan will tell me more, what would I be looking for?

Any and all fault codes. That's what the scan is for. To help point you in the right direction. This particular issue might need some data logging to find out what is causing the surging.

Got a VCDS!

What type of scans would you recommend for this? I have an hour drive to do tomorrow so I was thinking of running it during that time.