customer complained of erratic idle
hooked up scanner on live data the following
approx every 15 seconds
manifold vacuum altered
fuel trim altered
idle altered
accompanied by what sounded like a dump valve blowing
after various checks we found that if we blocked rocker breather all was well
removed rocker cover and found sealed breather valve built into rocker cover
contacted our tame vauxhall dealer and found out these were giving problems
now the pinch entire rocker cover required £122.00
ouch
thought might help someone sometime