First, even with newer coils, worn or wide-gapped plugs will “blow out” under boost and feel exactly like a random skip. Skip the re-gap trick and put in fresh OEM Volvo/NGK plugs, gapped tight (0.026–0.028″). While you’re in there, inspect the coil boots for carbon tracking and make sure the grounds at the cam cover are clean.
Next, sort boost control and leaks. A tiny charge-pipe leak or a torn CBV diaphragm won’t show up as poor vacuum but will stumble on tip-in and WOT. Do a proper smoke/pressure test of the intake/IC pipes to ~10–12 psi and check the turbo outlet o-ring and lower IC elbow. On the TCV: +1 to the question above, verify the hoses are on the right ports and not soft/cracked, and see if requested vs actual boost tracks in VIDA. A great A/B test is to run straight wastegate pressure (compressor nipple directly to the wastegate, bypassing the TCV) for a short drive; if the hesitation disappears, you’re chasing TCV/boost control oscillation rather than ignition or fuel.
Then confirm fuel delivery before buying injectors. If your car still has a serviceable external fuel filter and it’s old/unknown, replace it, it’s cheap insurance. In VIDA, log commanded vs actual rail pressure and pump duty during a pull; a pressure dip with rising duty points to a weak pump/PEM or restriction. If your PEM is still under the car, inspect the connector for corrosion; relocated trunk PEMs are much happier. Also watch trims: at hot idle and steady cruise you want LTFT roughly within ±5–8%. Big positive trims or trims that swing when the EVAP purge opens can feel like hesitation, temporarily clamp the purge hose to the intake for a short test to rule a leaky purge valve. A lazy front O2 at this mileage can also cause transient fueling weirdness without a hard code.
MAF “looks clean” isn’t the same as “reads right.” In logs, a healthy stockish T5 will show ~3.5–5 g/s at hot idle and triple-digit g/s at WOT; if your MAF is reading low with normal boost, it’ll feel lean and flat. If everything above checks out, then consider injectors, either a bottle of a PEA-based cleaner (Techron/Regane/Red Line) as a quick experiment or, better, pull them for ultrasonic cleaning with new filters and seals. Seafoam through the intake can help cold stumble, but it doesn’t do much for pintle deposits.
Fuel quality can exaggerate this (especially bouncing between E0 and E15 from off-brand stations), but it’s rarely the root cause. I’d start with fresh plugs, a boost/charge system pressure test, and a quick VIDA session (requested/actual boost, fuel pressure vs command, pump duty, STFT/LTFT). Post those numbers and we can zero in very quickly.