Going to remove the
BOV tonight any way to give it a clean... It has an adjustable spring pressure and i decided to loosen it off a little the other day to see if it would have any effect.
Strangely enough by loosening it (allowing it to release pressure easier the issue doesnt seem to occur as often or drastically. I've had the car running before watching the actuation of the valve and its not perfect/ideal. I'm think it might be a combination of both the TPS slightly out of spec and the
BOV internal sleeve not opening and closing smoothly.
Because its strange around 2500-3500 it will release air but just quietly, and theres not rev holding or spiking. though between 3500-4500 is when it seems at its worst and notably there is a real brief release of air or none at all. Anything over 5000 usually is fine.
Should note the car NEVER holds revs or spikes when its cold. and have had no idle problems since replacing the battery.
Will update after i fiddle tonight.