When starting car rpm’s go up and down and car shakes

Hi, my name is Devin. I am an auto repair expert with the Car Genius team here at RepairPal. I'm sorry to hear you're having trouble with your Passat. If your Passat is experiencing fluctuating RPMs and shaking during startup, especially when cold, it could be due to several factors. Common issues include a dirty throttle body, faulty mass air flow (MAF) sensor, or vacuum leaks. The engine control module may be struggling to maintain a stable idle. Cleaning the throttle body and inspecting for vacuum leaks might help stabilize the idle. If this persists, a diagnostic check could reveal if there's a sensor issue or an ignition problem that needs attention. If you need more advice, have any other questions about your vehicle, or would like to get connected to a RepairPal Certified shop near you, we have you covered. Give us a call at 877-913-1554, and we will happily help you out!