I have seen this problem on a lot of
engines generally its faulty plugs or the wrong plugs for the vehicle check them they should be changed I would say every 10,000 miles I would say and do not leave 17,000 miles between serviceing or you will be asking for trouble .
But some injector cleaner in as this engine can be known for carboning up . When your tank is empty bob in the req amount and fill . I feel this may help but first change plugs
Make sure you get the right ones the ones for the
engine and renault only plugs other wise you will get a misfire under load .
With the mileage you have on your vehicle I would take it to renault and ask for the plugs to be changed this may cost you £60 but they should have it on the computer and also if it is anything serious you should get a warranty payment as I believe your vehicle is just over three years old but with that mileage they should still pay depending on whats wrong with it .
Before you take it in check your airfilter if it is mucky that could be your problem .
Or the fuel pressure reg none of these are an expensive job .
Anyway what are you doing 120 mph for
Hope this helps