Acceleration issues

[the bull]

Hi all I have a 2011 2.2d xf, the car is great when cold accelerates great no issues, on long motorway runs again no issues, but when I drive around town about 7-10 miles stop start I get some series acceleration issues, the car is very unpredictable sometimes it pulls away slowly and picks up gradually, other times it pulls away lime a snail and very slowly picks up, I have no error codes or fault lights, I have changed the MAF sensor, had the EGR valve programmed out of the ECU and changed all filters and can't find the issue, when the problem occurs if I put my foot to the floor it revs to about 3000 rpm but doesn't pick up and the gears are snatchy, I have had the transmission serviced and checked and that if fine any help would be greatly appreciated. 

[Max Castril]

I had a similar problem with my S Type and the mechanic found a perished vacuum tube (black rubber 10mm approx) going to the engine block.  On replacement, the problem went away.