Hi there
One of the things you need to get really clear soon is if you have leak in the induction system. You need to pressurise it and to do so and try to identify the leak. Normally is from one of the large pipes, but it could be from the intercooler, for example. If you don't have leak, the next step is to test the wastegate - pressurise the small hose feeding it and see if it moves well. If this reveals no deficiency, it can be a missfire or lack of fuel.
I had a Lancia Integrale 16V with a small missfire that would be only noticeable with boost and wouldn't allow the turbo to go over 0.5bar