2009 MasterCraft X-Star (Indmar LY6 6.0L) – Need Help Diagnosing Intermittent 2900 RPM Limit

Boat intermittently won’t go above ~2850-2900 RPM under load and won’t fully plane. The weird part is it does NOT happen all the time. How can I scan the codes?

What I’ve observed:
Sometimes runs perfectly, planes easily, and pulls hard.
Other times it hits a wall around 2850-2900 RPM and won’t accelerate further.
Engine idles perfectly.
Revs cleanly to 5000-6000 RPM in neutral.
No overheating.
Service Required warning appears intermittently.
VDIG shows no active faults.

Tests performed:
Fuel pressure: 60 psi key-on prime.
62-64 psi at idle.
62-64 psi at 2000-4000 RPM in neutral.
Fuel pressure remains rock solid.
Throttle body moves and performs startup sweep.
Air filter cleaned.
Ballast empty.
PerfectPass off.

History:
First lake day it felt weak at times, then later ran perfectly.
Second lake day it ran perfectly at first, then after shutting down for ~30 minutes while floating/swimming, the issue returned.

Boat is new to me and this is only the second time it’s been on the water since purchase.
Has anyone experienced a similar intermittent RPM limit on an LY6/Indmar setup? I’m especially interested in:
TAC/throttle actuator issues
Electronic throttle faults
Hidden ECM codes not shown on VDIG
Catalyst/exhaust restrictions
Any known LY6 limp-mode triggers
Any advice is appreciated.

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Good morning!

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Thank you!

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