Ive got a mk1 octy vrs with 105k, sat at a junction on the way to work and the idle goes from 1000 rpm and drops to 500 rpm then back up for a second, it doe this every 10 seconds or so!!!! Any help or advice please?

Remove & clean the throttle body.

+1 for TB Clean

then if you still have issues you are looking at breather pipes etc (pre turbo)

Cheers guys, I'm a bit useless at this stuff so how do I go about cleaning? Wot do I need to take off? Cheers

This is from UK Mk IV's

Awesome! Will do it this afternoon thanks everyone x

Ive got a mk1 octy vrs with 105k, sat at a junction on the way to work and the idle goes from 1000 rpm and drops to 500 rpm then back up for a second, it doe this every 10 seconds or so!!!! Any help or advice please?

Sounds very similar to mine - the idling on my 2001 vrs doesn't seem quite right and then does exactly as you describe but not as often. Also on start up sometimes the revs don't get up above 500rpm no matter how hard I press the accelerator. switching engine off and back on is only way to get going.

First started playing up around March last year and seemed to clear when the weather got warmer. Come October problem started again so suspected it was a damp weather issue. Left it with the local garage who couldn't find a problem with it. Took it away expecting to to be cursing them before I got very far but has been fine till now!

Would be interested to know how you got on with the throttle body cleaning and whether it cured the problem.

I had this ... turned out a little car suicide bomber terrorist ran inside my 'Y' piece breather pipe and pushed the button.

Changed it and it stayed up and down for a little while then it kinda like re calibrated itself and now its mucho sexc time!