I had the issue on my Audi where the fuel and temp guage were temperamental... So I sorted that out but disconnected the battery first as had to remove airbag.

When I put the battery back on, it was low for some reason and car wouldn't start.

So I took the battery out and charged it at home.

Put the battery in and started the car and it started to idle very high until it finally dropped to 1,500 and started to bounce to 1,700 every second.

I've tried the idle reset by pulling ecu fuse and turning ignition for 5 seconds then off then start again but same thing... Revs constantly bouncing.

I've searched for vacuum leaks and none found. Tried vagcom (free version) and no error codes...

Any ideas?? Can someone help? MOT due in 2 weeks and it decides to do this 😣