Hi, I am new to this forum and apologize upfront if this question might have already been asked before. I could not find the answer. I drive a 98 Sirion 3-cylinder 1.0 12V (105k miles). Last week the engine ran rough and it had no power like it used to. I brought it to my mechanic and he told me it’s because of the spark plugs. He has changed all three plugs and said it runs fine again. I picked it up today and still find it running rough, a bit more power has come back tough, but the engine still doesn’t sound like it did before. It does not run smoothly, not even when it has warmed up. I now wonder if it might be an ignition coil that started to fail/has failed? Any experiences with my engine symptoms?

Thanks!