Strange shudder on idle

[ghost.197]

My car's developed a strange shudder on idle. It happens about 80% of the time - so it's not always there. And it varies in strength - sometimes it's more noticeable that others. When it does shudder, it happens at 3-4 sec intervals. I've checked things like plugs and coils and had a quick look at the intake pipes, etc. I was fiddling about in the oil filter area a couple of weeks ago, is it possible I did something to the knock sensor?

Any help would be appreciated.
Thanks

 

[Foxspeed]

just check all the connections are on the multi-plugs correctly

it sounds like its ticking over to slow and the revs are dropping and then coming back up again to stop it

it could be an air leak or a sticking throttle / choked with carbon/oil

 

[ghost.197]

Thanks for the tips, fox.
The sparks and coils got a good clean yesterday which seems to have helped, so I'll keep an eye on it for the next few days and take it from there.

 

[Roy]

How old is it ????

 

[ghost.197]

It's an '07. With about 70 000km (about 43-44 ooo miles).