Outlander has a rough idle, hoping to find a proper garage

I've got a bit of a mystery with my 2017 Mitsubishi Outlander that's been driving me up the wall for the past couple of weeks. The car starts fine and runs perfectly on the highway, but when I'm sitting at traffic lights or in heavy stop-and-go traffic, the idle gets really rough and lumpy. It almost feels like the engine is going to stall sometimes, though it never actually does. I've already done the basics, cleaned the throttle body and replaced the air filter, but it hasn't made any difference. I'm starting to think it might be something more complicated like a vacuum leak or maybe an issue with the fuel system. I took it to a local garage who just plugged in a generic OBD scanner, said there were no codes, and told me not to worry about it. But I know my car, and this definitely isn't normal. I'm not comfortable driving around with it feeling like this, especially when I have to do school runs with the kids in the car. I've been looking for a place that actually specialises in Mitsubishis and has the proper diagnostic tools to properly figure out what's going on. I stumbled across a website, alzaabiautocare.com/brands/mitsubishi/, that seems to be a specialist workshop for Mitsubishi models, which is exactly the kind of place I'm hoping to find. It looks like they actually have the manufacturer-specific software that can read the deeper codes that generic scanners miss. I'm planning to give them a call but wanted to see if anyone here has used them before or can recommend another good independent Mitsubishi specialist in the Abu Dhabi area. Would really appreciate any advice because I'm genuinely worried about this issue getting worse.