Engine misfire?

Hello, I have the vehicle listed above 3.0t. I bought this car and when I bought the car, I changed all the regular stuff, new spark plugs, crankcase, everything in that, water pipes, all the stuff that comes with needing replacement in an Audi. In my car it starts perfectly on a cold start and has never misfired on a cold start. Now when I start it up and drive and the engine warms up a good amount and go to park my car and let it sit for about an hour or two that’s when the misfire starts. The misfire would consist of the car starting but not the engine and just going to 0 RPMs for me to start it in this case I would have to tap on the gas to start. I took my car about 4 months ago to a mechanic and I was told it has something to do with an ECM unit of my car having water damage. I also get to check engine lights on stuff that I don’t think is an issue in my car so it’s also throwing false alerts. So, I was wondering would I proceed with getting an ECM replacement and do you think this would fix the whole issue and not dealing with misfires. I would really appreciate the help!