Try the Tdc sensor in the front pully. there might be some dirt lodged there, or the plugs, a few years ago I was washing the car with my young son and he decided to wash the cam cover on the engine letting water down on to the plugs. The car developed a random misfire and I coulden't figure out why, I checked everything and then checked the plug holes and they were full of water
. On my brothers dedra it developed a miss fire and we traced it to the tdc sender wire that was rubbing off the power steerimg belt as it wasen't fixed to the engine, eventually it cut right through the wire, We had some fun finding it
