Ford Focus diesel 2006 Mk2 2.0 tdci low rpm Judder / Vacuum hose sizes

[DB_Focus]

 

I'm new to the forum and did a search but didn't find exactly what I was looking for, if it's already been covered perhaps someone could point a newbie in the right direction.

Problem = Judder/stutter at lows reves (1500 to 2200 rpm).  No warning lights on dash.

Possible causes = Italian Ford garage thought it was a fuel problem but didn't have time to fix it.  It was fine on the 450 miles trip down but with around 80 miles left in the tank the problem started.  It doesn't have any starting problems.

I suspect it is a vacuum hose leak related to the EGR or throttle body.  Any other possible causes it could be?

The car is now 12 years old and as I'm in Austria where the winter / summer temps are more extreme than back in the UK various rubber bits have recently failed.  e.g. I recently replaced the intercooler hose at the beginning of June, the car ran great until last week.  I have road recovery cover with the Austrian AA equivalent and the car should be delivered back to me in the next 2 weeks.

Looked on YouTube and saw a guy replacing the small vacuum hoses on a similar diesel engine with silicone hoses. 

 

Irrespective of the cause it's probably prudent for me to do this anyway.  Have found this diagram

http://kmestc.com/2006-ford-focus-vacuum-hose-diagram/2006-ford-focus-vacuum-hose-diagram-luxury-repair-guides-vacuum-diagrams-vacuum-diagrams/ 

but can't find the sizes and don't have the car so I can't measure the internal & external diameters.  At a guess I would say they are around 3 to 4mm internal diameter.   Can anyone help?

Thanks in advance for any helpful replies.

 

 

 

 

 

 

 

[DB_Focus]

Just to add -  the problem becomes more evident once the engine is up to temperature.