I have a 3 year old 307s (1.4l).  It has been running fine since I got it but
I recently went on holiday and after about 300 miles the started to car
judder violently as I fully released the clutch when going into second gear.
This sometimes happened trying to get it into first and third also.  The only
way of preventing this was to massively rev the engine.

I did have a lot of weight in the car, but I have had similar weight in it
before and have had no problems.  When the weight was out of the car I had no
problems with it at all.

Is it serious?