L700 idling problems

So ever since i got my l700 it did idle a tiny bit below what i believe it should be, but yesterday i went on a trip with it everything was fine I was going around 110 ish for the entirety of it and then I stopped for a coffee and suddenly the car was idling very rough even stalling after about 5 seconds any clues as to what might be the cause of this

Have you pulled the plugs out and inspected them to make sure they look like they are doing a clean burn? I recently had the rocker gasket replaced and oil was leaking into the spark plug chamber causing them to foul slightly, impairing a smooth idle and the car would run a bit rough at times at the lights, etc.

How empty was/is the fuel tank if it was ran close to empty it could have sucked up some crap from the bottom of the tank especially if the fuel filter is old. If you fill the tank does it go away?