Hi, my clutch pedal occasionally looses resistance in the first couple of inches of travel, it feels as if its going to go straight to the floor. It springs up ok, there's just no pressure for a couple of inches when I depress the pedal. It comes and goes, literally one moment its limp, the next its normal again. Is my master or slave cylinder on the way out? Or is this down to weather/air pressure changes or something? Cars done 100k and I'm planning a 3000 mile drive in a few months and I want to sort any problems before that.