In a word, NO. The pressure takeoff is on the side of the turbo, and connects directly by a hose to the actuator. The actuator holds the gate closed until the specified pressure, so even if the hose was open or blocked, there would be boost.

Actually, it means that one glow plug is open. Replacing the glow plugs on this engine requires the cruise actuator, crossover and intake manifold need to be removed. For the trouble of removing all that, you'll be doing all five plugs, so there's no point in figuring out which one is bad. Trying to do it without removing all that stuff is like building a ship in a bottle. It's a lot for a first project.

It occurs to me that what you may be seeing isn't a boost problem at all, maybe the transmission is downshifting early. This can be caused by something as simple as an accumulation of dirt between the accelerator pedal and the kickdown switch. Are you sure this isn't the case?