My car ran badly for a little while today and a similar thing about a week ago.
Normally it's fine, then all of a sudden it started running rough; down on power, needs more accelerator and using more fuel. No warning lights or similar. Stopping and turning it off and on didn't seem to help. Turning it off and locking then unlocking the central locking with the key seemed to fix it both times. It felt a bit like it wasn't running on all cylinders.
The rest of the time it's fine. It's got 165,000 miles on the clock, the last 40,000 done by me over the last 18 months. I've always had it serviced by a good independent except the most recent minor service about a month ago which i did myself (I just changed the oil, filter and topped up the power steering fluid).
It's lpg converted but I don't think this is the problem - i switched it back onto petrol and then onto lpg again when it was running badly and it didn't make any difference.
Any thoughts gratefully received!