once again my p38 4.6hse is overrevving on tickover at 2500 rpm
i have changed or checked:

stepper motor
cleaned filters
checked air sensor
checked flexi pipes

anyone got any ideas

I think your engine ecu is failing to see a closed throttle position,make sure there is free play on the throttle cable.If the ecu doesnt see an output voltage at or below its "stored closed throttle" voltage it will hold the stepper motor open ready to close it down in stages to provide good emissions and make sure it does not stall if it comes under sudden load.(power steering,alternator etc)
The only way to check this is by testbook etc,when it becomes very obvious.The stepper position should be around 15-30 steps at idle,hot with A/C off.The stored closed throttle voltage needs to be .6-.85v - any less than .6v and it will tend to stumble just off idle,possibly causing stalling issues.Hope this helps.