Hi, well Jens got me on the right track to check this valve. Indeed it is not right. When I pull the electrical connection the engine dies within a short time (a number of seconds). According to BenzWorld, it should have increased the idle rpm (an indication the valve is good). I'll be pulling this valve off and cleaning it... however, is the engine stalling a specific sympton for anything while I'm in there? with the electrical plug connected the engine revs at 500 when in gear and around 700 when in P or N the idle also is not 'particularly' smooth, not bad - but there is a bit of surging.
cheers, guenter
ps DIY's have -got- to love the internet