[ngoma]

Yes, also check valve clearances.

Check compression again with a diesel (higher gauge range) compression tester.

If the problem is at the IP, it probably would be the delivery valve as the IP is a rotary style (one piston pressurizes all the lines).

When testing injectors it is important to test spray pattern (which you did), and also POP, and drippage. Must not drip or even moist at the pintle needle when sitting at just below POP for 10 seconds.

Probably the quickest next step would be to swap the injector to another hole, see if the problem follows the injector. Make sure you have new heat shield washers, or are able to reform them.