I remmember my problems and questions about amal valve

ok..if you have faulty amal valve you will have only about 4 psi of boost.

yes you can check actuator, but need bleed valve (boost controler) or you can simply pull out hose from turbo (turbo-actuator hose) and suck air with mouth and make little vaacum on actuator, it must hold vacum about 20 seconds...

I think it is amal valve making problems here... so just try run with it , and after that, dissconect power from amal valve (dont remove hoses for air) and if there is no diference it is knackered.