Engine surge when braking

[ahmorris]

I have a late 98 E320 Avantgarde.

Everything works very well (my 1st E320 and I'm very impressed) but have a small problem that if I brake heavily after the engine has been revving high (eg. travelling down hill, accelerating then brake etc.) then the engine surges ie. revs increase momentarily.

The problem does not happen all the time and I have yet to find out what triggers it eg. weather, engine temp, driving period etc. or to replicate it easily when I try to explain it to a mechanic.

Anyone have any ideas what it is and more importanly how to solve?

[Kajtek1]

Sounds like a leak on vacuum lines, or brake booster.