Hi car is 2005 vRS and under hard acceleration it seems to "lurch" forward in a pulsating manner - sort off feels like handbrake is being applied slightly and rhythmically whilst accelerating or fuel not being delivered smoothly.  Pulsing is every half second or so - really weird sensation.  All other aspects seem fine.  Any ideas?

Search for boost surge, spend hours of your life reading all the causes. Typically boils down too boost leaks, dodgey charge pressure control valves (N75) or leaks on vacuum lines.

if there is an aftermarket DV replace with standard or use a service kit (forge)