I have a 2012 Prius with 298,000 miles (I know, right?!) I hear a rattle on take off at low speeds of 5 miles per hour, have had the exhaust system repaired as well as checked out by multiple other mechanics. It’s esp bad when hot and I feel like it’s going to stall but it hasn’t. Anyone know what’s up? Rattle has been present for years !
To help start narrowing it down ... does it happen in EV mode, or only when the engine is running? Reverse as well as forward? Confirming your description - takeoff meaning that while the car is sitting there with the engine idling there is no noise, and then when you start to drive away the noise happens? No noise when revving the engine while stopped? But to lower your expectations, if you've had mechanics inspect your car and fail to find this, it might be tough for us to do it based on a written description. I bet any of us would come up with better guesses if we had the car in front of us.
Yes, very hard to diagnose this over the internet. Why do you feel it's going to stall? How much of this "stall" feeling is connected to the rattle? Not sure even with these answers I could offer much. Best bet, would be to have your mechanic/techniciian ride in the vehicle and duplicate exactly what is happening, when it is happening.
