90 300 SL

Hi,
There seems to be a huge vacuum leak somewhere that makes breaking very hard (need extra force) and , at kickdown, it takes longer to shift down.
Duty cycle fluctuates at about 85% (very lean). I check vacuum lines connected to the engine manifold etc, they are OK. Where else can I check?

Thanks

__________________
Zorin

'88 Benz 420 SEL
'79 Porsche 911SC ('87 Carrera Engine)
'00 BMW 540 Sports Package
'99 Land Rover Discovery

86 300E - Manual (sold)
88 260E (sold)
84 944 (sold)