Laguna 1.8 cutting out when changing gear

Hi, my 2001 1.8 16v Laguna2 has recently started acting up, it starts and ticks over fine-drives perfectly until i come to change gear. When i dip the clutch the revs drop right down to 3-400 sometimes cutting out, after a couple of seconds it picks back up and idles ok. It only does this when its warmed up and not when cold.

Has anyone else had this problem or anyone know what could be wrong as it is becoming quite a problem when driving and I lose steering when changing gear for a junction.

Any help or advice greatly appreciated



Pete