Laguna2 1.6L possible misfire

Over the past few weeks at idle it doesn’t seem to be as smooth as normal.
Acceleration was good – light and heavy load.

This morning acceleration under light load is good, under heavy load it isn’t.
There are no dashboard warning lights.
I had the throttle body replaced last June (but forgot to get it re-calibrated, but the car has been running fine, with a good MPG/tank range).
Spark plugs / filters were also changed last year.

I’m guessing that as there are no warning lights there’ll be no error codes?
So thinking about this and after reading other posts on the subject in my mind it points to possible coil pack failure….overfuelling and not correctly sparking.
I did notice last year when I changed the plugs that one of the coil packs was different to the other three, and I think that I identified that the 3 were Renault and the fourth was some proprietary make.
I have had the car for 8 years (and it’s 15 years old this year), and coil packs don’t have a lifetime of working – would these likely to be the cause?

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Laguna2 1.6L possible misfire