Mondeo exhaust leak and rough running

Sounds familiar. My old Opel Astra had the same symptoms, turned out to be the catalytic converter. Is yours okay?

I haven't checked the catalytic converter specifically, but wouldn't that trigger a specific error code? The car doesn't have DEF fluid or a particulate filter, so I'm not sure what else it could be.

True, it should throw a code. Mine did eventually. But the symptoms were identical at first. Take it to a workshop and have them check it out thoroughly.

I took it to the workshop, and you were right, it was related to the exhaust system. The lambda sensor was defective and was causing the entire malfunction. Replacing it cost me 375€, but now everything seems to be working fine.