Timing wouldn't affect just one injector. Having said that if you have never checked the timing before you probably should. Have you tried swapping the suspect injector to another cylinder and seeing if the nailing follows?

How does the pre chamber look? The ball should be pretty tight and it should be clean. Are you sure it isn't a lifter acting up?

__________________
2006 CL500
2009 C300 4matic
1969 280SE
2023 Ram 1500
2007 Tiara 3200