Power cutting in and out (also oil in air filter)

[xbaboon]

Over the last few weeks I've noticed my M-reg 1.3 Polo losing power quite regularly. A couple of years ago I had something which felt similar, and after a bit of poking around I replaced the HT leads and it's been fine ever since. This more recent problem is very strange though. I can be driving along quite happily when it suddenly feels like 1 or even 2 cylinders have dropped out, and the car crawls along. With no warning or regularity it can happen, and similarly as it kicks back in. I can feel it dropping in and out now and the difference it makes.

I had the bonnet up yesterday and a new set of leads, but before I put them on I thought I'd just check the plugs too. They're all clean, no soot, and when it's idling it doesn't sound like it did when one wasn't firing. The leads all look fine too, they've only been on a year and a half and show no signs of rubbing/cracks/damage. The main thing that struck me as wrong was when I took the filter off to get to the plugs. There's oil sat in the top of the dish, over what looks like a breather (I'm no mechanic!), and dirty looking oil in the filter itself. Some kind of blowback?

I took the oil filler cap off and checked, and there's no drips/milky colour, so it didn't immediately scream head gasket at me. The only things I've had suggested so far other than leads/plugs is possibly a sticky valve or ECU.

Has anyone got any thoughts or something else I should be looking at?

Thanks in advance.

[kingsleysaywell]

HMM I want to know about this 'Blowback' as when I changed my standard filter to a BMC CDA I noticed this aswell

[Tim_GTi]

How's your temperature readings?