eratic idle

[cyman]

my rex idles perfectly when you first start her up but when its hot it has a tendency to hunt upto 1500rpm then drop back to 1000rpm for anything from 10-45 secs then it settles down to a nice 6-800rpm solid tickover.
 
the car is non sequential so no rats nest. it is due for a re map update to sort out the higher rpm which will be done soon. the car pops a bit if you hold the throttle at say 2000rpm but i remeber my old one did that so i havent thought thats a prob and besides this it runs sweet and pulls like a train.
 
i have had a look and a listen for any obviuos pipes off/vaccum leaks but cant find any.
 
anyone got any thoughts on this???