deffinately not an air leak, checked the pressure in the manifold with a mityvac and its 20 bar but does flicker a bit, but its not valves a a compression loss test should have shown that up. haven't got code number on me now, but it just said misfiring with cat damage ( possibly p1420?) not random multiple like an air leak either, and map values check ok, was wondering if these had hydraulic tappits? and if they hold under a compression/compression loss tests even when faulty?