Looking for a bit of advice on an issue im having with my A3. Car starts fine, no issues, but when i set off and change up in gears there's a noticeable drop in power immediately after changing... Most noticeable between 2nd and 3rd and 3rd and 4th. The car never used to be like this and it only started happening after i put some deisel fuel treatment in the engine the last time i filled up...
The best way to describe it is that the car seems to struggle to adjust to the new gear for 1/2 to 1 seconds before resuming acceleration as usual.
any ideas on what this might be? Already spent 2.5k extra ont his car since i bought it 11 months ago and I'm dreading this being the start of yet another wallet burning crusade through the audi garage.
Thanks in advance!