Idle speed suddenly dropping.

[paullus]

Hi.
My car S70 2.5T LPT with RICA 235 remap has sddenly developed a very intermittent fault. Without any warning the idle speed suddenly drops to about 600rpm and then surges up and settles back down. It does this a couple of times and then it's ok. It starts up and drives fine otherwise.
Mine is the earlier version without the ETM.
Any advice welcome.
Thanks.

[paullus]

Blatant bump!
Has anyone else experienced this?

[Plodmonkey]

Me don't no what it is does it randomly sum times a few blips of the accelerator peddle helps it go away

[danny-R]

mine also does/did this......

[M-R-P]

Mine does it sometimes, I'd be sat at the lights and the revs drop and then come back up, as if it's just engaged the clutch on a very big AC pump.
Dirty throttle?

[MobyUK]

I'm having a slightly similar problem. When I'm on overrun at slow speeds, less than 30mph, I can feel engine braking going on and off as if the throttle is being pressed. It's a bit of a pain when you're in town traffic.