406 turbo diesel clue

Hi Guys,
my car ( 406 turbo diesel ) will play up every time it
starts and I wondered if anyone else has this?. Now here's the clue, I've
noticed that if I turn the ignition key and the rev counter goes to full
scale then back down the car will then run rough and noisily. However if I
turn the key and the rev counter just jumps up and returns to idle straight
away the cars performs as it should.
So what causes the car to do this , can anyone point me in the right
direction please? Thanks for your time.

Regards,

Andy Sarbutt.

 

Don't know why this happens to a diesel, mines a petrol and sometimes do
something similar if it gets flooded, e.g. I inadvertently press the
throttle before switching off, this will flood it, but cant be the same on a
diesel, maybe something to do with the turbo!
sorry I cant help any more than this regs, mark.