nasty misfire

[andy]

Got a problem with the UR, it has developed a nasty mis-fire, not constant but happens 90% of the time, cant get it out of first. Also when i rev it and then walk round the back of the car its spraying alot out of the exhaust, water i think.
have checked that all plugs are sparking and thats ok, thought maybe head gasket but have checked the oil and its the right color and no coolant is missing.
few weeks ago there was a problem with a wire behind the glovebox and if it was knocked then the car wouldnt start (glovebox was off) so just taped the wires and she fired up, could this e related??
many thanks,
Andy