Cam retard 12° to 15° is normal.
Vacuum 15" is on low side (but still considered normal) but you must take into account the BARO reading before you make that decision.
Some of the specs you are looking for are in the manual. But most of them are numbers that change with the local conditions. Like altitude, fuel quality, temperature and humidity are just a few. Because of the many variables involved. The tech is assumed to know what numbers to be looking for based on experience.
I wouldn't worry about the post cat O2. It's main job on your engine is to monitor the catalytic converter efficiency. The pre cat O2 is what controls the fuel trim. A failed Post-cat O2 sensor can NOT cause an engine running problem.
Long term fuel trim -10% to -15% is normal. It can go over 35% negative or positive before a code is set.
A perfect running engine (at steady speed, steady load) would have a long term fuel trim reading between +15% and -15%.
Post cat trim off is normal. The post cat O2 only changes fuel trim to make slight adjustments to increase catalyst efficiency
.
CLOSED + ADAPT is normal. It just means that the engine is in closed loop and is now able to write the short term fuel trim to the long term fuel trim tables.
Your engine should switch from closed loop to open loop when you reach higher RPMs. That's how the system functions.
If you want to post the test sheets you have, I can take a look at them to see if anything looks wrong. But so far everything you have posted leads me back to this list.
Engine Won’t Reach Operating RPM
1. Fuel type or octane
2. Propeller pitch or diameter, damaged blades, slipping hub
3. Crankcase oil level
4. Marine growth on hull and drive
5. Wrong Sterndrive gear ratio
6. Operating at high altitude
7. Restricted air intake
8. Restricted exhaust outlets in engine, transom bracket or drive
9. Poor cylinder compression
10. Fuel pump pressure and vacuum
11. Boat overloaded, or load improperly placed
12. Engine overheating
13. Engine timing and ignition system operation
14. Remote control cables and linkage for proper attachment and
travel
You really need to think about what could have changed from when the engine would reach full RPM and now that the engine won't go above 4,000 RPM
You NEED to rule out ALL 14 items.