M.B.Doc thank you and please clarify: your statement "with removed..." should be "with removed vacuum line...". So pressure should be 3.4-3.5 at idle and 3.5-4.0 at full throttle.
It means that I'm about .5 bar too low in both cases. But it also means that my pressure regulator is regulating correctly - it lowers the pressure by about 600mbar at idle. And I 've already checked that regulator is not leaking so why do you think it might be deffective?

It looks to me that for some reason I can't build enough pressure because: pump, injector leak, other leak in the system or...? But I'm not 100% sure why low pressure would affect only one bank. Unless it is a leaking injector which creates both pressure drop and sensors issues.
So my next step is to check injectors. Any other suggestions?

PS. Gmercoleza: no gas in the vacuum and regulator is moving and regulating. Thanks.