Fiesta rough idle stalling

Those symptoms sound familiar. I had a similar issue with my old Opel Corsa, though it was a different engine. Rough running, stalling... the whole shebang. Have you checked the ignition coil pack? A faulty coil can cause misfires. It might be worth a look before you dive into anything more complex.

When you had this issue with your Opel Corsa, did the vehicle diagnostics specifically point to the ignition coil pack, or were there other potential causes?

In my case, the diagnostics pretty much screamed 'ignition coil'. It was a clear-cut misfire code. Given your symptoms and the age of your Fiesta, it's a strong possibility. I'd recommend getting it properly diagnosed by a workshop to be sure, as messing with the ignition system can be tricky. It could save you a lot of headaches.

Following your advice, I took the Fiesta to a local workshop. The diagnostic confirmed the ignition coil was defective, traced back to a corroded connector. The repair, including parts and labor, was 95€. The vehicle now runs smoothly. Thanks again for your valuable input.