bost problem

[g18mar]

when driving bost gose up to .75 bar the drops back to nothing the gose up to .5 of a bar then drops to nothing then .5 and back then .5 and gose on like this intil i change up a gear the same all over again

any one had the same problem

[PLB]

max boost=max trottle(no in 1.,2., ger due to limiter)! it shouldnt be max boost all the time. during cruising on highway...ther is no positive presure in vacums system att all.
if boos flucuates a lot, mabe wastegae valve or actuator is stuck..