what year is yours, I have just been looking at the fault codes on mine, and despite knowing I have put it into limp mode several times, still there was no light or codes, so I don't think the ones around 1999 are as good at recording these events as the later ones.
My guesses for yours are, fuel filter, air getting into the system, or a leak in the intercooler/connecting pipes.
Over the time I have had mine, I have had a few issues regarding these items, and most seem to show up most as the Turbo kicks in at about 1800 to 2200 RPM.
I would start with checking the intercooler pipes and their clamps, as the original Nissan ones are not very good, and loose their compression over the years. Next, the Fuel filter, and change the 2 flexible pipes for clear, to see if there are any air bubbles in the system.