Mazda 3 idle issue ..help please

ferry

Hi all
I know there are a few mechanics on here so just need some help with my Mazda 3 2006 petrol
Its a bit of a strange idling issue where the revs would just randomly 'dip' for a split second and then recover every couple minutes or so only when stationary
I did get a management light come and code suggested the purge valve which I replaced (common issue on these). Code reset and has not come back on but still the issue persists

So, bearing in mind no codes or dash warning lights are lit now and runs spot on.

Tried so far: TB clean, MAF and though live data software showed no ill signs, no vacuum leaks (basic spray test) ECU reset as 'recommended' by Mazda,
Redex and good run out never helped either so now I'm a bit lost
Any ideas greatly appreciated

F