Same as before. Electrical in nature, can hear the relay in the engine bay clicking when it misses. It has been like this for some time, on and off. I've replaced:

Coil pack (Megane one)
Spark plugs (several times)
Crank sensor (twice)
TPS (special one for ITB's/Jenveys)
Rewired crank sensor
All relays replaced
ECU sent to Emerald ECU's for testing (was some scrambling to code due to some kind of electrical interference)
Swapped to Walbro performance fuel pump
Rewired pins for power and crank sensor on ECU harness
Rewired main wiring for ECU/Ignition/Fuel pump relays

I've had a leaky camcover for ages, it is NOT the seal or the head itself as both been replaced and it still leaks into spark plug well no.2 This itself fouls the spark plug and causes a loss of power and generally rough engine revs. I had a theory the spark from coils could have been discharging through the body of the car causing damage somewhere as the oil levels in the spark well got very high.

It could be something shorting out, or an old part of the wiring loom I have not checked I guess.

I have no problem starting the car and it does not happen when I just start the car from cold, it only seems to be when hot usually.

I cleaned the oil out the other week and last night and replaced plugs last night again but although it felt nicer to drive, the misfire started again on the way to work.

Might take it to Emerald themselves and let them play with it, this is doing my nut in! Always happens when I least need it to happen as well...