I’m facing an issue with my IS300 2021, when I start the car RPM struggles for a couple of seconds and keeps shaking then it goes to normal range. Any one know what could be the problem?

the car is new with 10k miles on it.

 

Not sure but I wouldn't spend a lot of time figuring it out. I'd just take it in and let warranty deal with it.

Has it always done this or is it a new issue?

 

Welcome to CL as a new poster.

A common reason for RPM and shake problems on a cold start is a lean fuel mixture (too much air/not enough fuel). In a modern vehicle with electronic fuel injection, that could come from a number of sources.....among them clogged injectors/fuel lines and bad engine-sensors.


All else equal, a cold engine needs more fuel and less air to run properly because the fuel does not vaporize as easily at lower temperatures. That is one reason why gas-mileage suffers in the winter and/or with a lot of cold starts.

 

I second this. Just take it in to the dealer, it's probably just a sensor or a hose that got disconnected