"Misfire Headache"

Hi all. I have a misfire problem with my 2006 vrs (petrol) that has been bugging me for last two weeks. It all started when the car sort of kangaroo'd violently for a second or two then went back to normal. About two days later it it started to misfire under load/boost (high gear low revs). and the emissions/exhaust system light flashed a couple of times then went out. Eventually the light came on permenantly and the misfire continued. I eventually got it scanned by a mate for faults and it gave me P0300 & P0304.

I changed all four coils and this seemed to cure the problem the light even went out itself before i had a chance to get it turned out but a couple of days later same problem all over again. Car has done 40,000 miles and plugs were changed about 5k miles ago.

Car is out of warranty now so any help would be appreciated. Once you take these problems to the dealer they end up replacing all sorts and it ends up costing a fortune.

Thanks and any advice/help would be much appreciated.

It is driving me insane!! :confused: