stand facing the engine bay, look at the top left of the bay and you'll see a rubber 90 deg pipe, on the end of that is your EGR/ASV(ex gas re-circ and anti shudder valve)
to check if its clogged up, remove the pipe and have a look inside with a torch, if it is clogged up, keep reading..........
that part is bolted onto your manifold with 3 bolts(5/6mm allen head i think) remove them
there is a pipe that goes from your exhaust manifold to the EGR/ASV, it's 12m nuts on the bottom and 5/6mm allen at the EGR. remove that pipe. EGR/ASV will now come out.
the inlet manifold is held on by 6 bolts, 6mm allen key is required to do this, and you'll need to unhook the turbo inlet(10mm spanner top and left side) and unclip the pipe from the MAF and push the turbo inlet backwards to get better acess to the manifold bolts.
once it's off remove the anti-shudder actuator(torx 30 i think) from the EGR/ASV and block up the vac in bit at the top to stop getting any water/detergent in there.
then get some de-greaser and leave to soak in hot water, probably be best off with a big pipe cleaner for the manifold too.
once dried re-fitting is the reverse of removal
but use a new inlet manifold gasket. then unplug the top vac hose and block it up and it will never get as gunked up again