As the family go-to guy for fixing things I recently got asked to have a look at a young lady's 2005 1.4 Megane for a very similar sounding fault to yours. The symptoms were a worsensing running condition until a point was reached when it would start but was really lumpy running, which then developed into a no-idle condition and the car became undriveable. The fault light was coming on too.

I checked the fault code and it came up with that very generic code of misfire, possibly coils. Detaching individual coils made no difference - it was nasty no matter which one I disconnected. I then had a look at the plugs, which were in an awful state because at some point some numpty had obviously high-pressure washed the engine (the plastic engine cover was missing) and filled the long tubes that the plugs are located in with water and it was all very rusty and quite nasty.

Anyway new plugs did not fix it but they needed replacing because of the deep rust on them so it wasn't a waste. Anyway before spending more money I did some research and this model most definitely has coil problems,so it was the coils I targeted. They are quite cheap and four new ones fixed it good and it is perfect now.

Running your fuel tank down may or may not be the problem. However Renault Meganes have a loooooong history of failed coils and running a low tank may just be a coincidence with failing coils.

Check the www. and have a read up on these coils. You may find it could be the coils.

Regards

If you ran on fumes, the fuel will have picked up all the tank debris and dumped it in the fuel filter.

Change it.