I just reread your note and had it backwards. Noise is there until you accelerate. I would loosen each Injector line starting at number one. Might be a bearing or part that will respond to a lesser load. Number one on these engines is always a prime suspect. When you say you were low on oil I assume perhaps low enough oil pressure dropped off? Sounds like something started to go and is getting worse with time. With something like this occasionally a good full time working mechanics guess or opinion is important. As the noise is increasing time may be important here. Ten times injector noise is pretty loud come to think of it. The cam may not have liked the low or no oil either. You may want to inspect that as well. I might still inspect the chain as well for slack or other problems. The same thing applies though. It is a little hard to include every nuance in a sound description and something we leave out because we do not actually absorb it to describe it. Or it cannot be described well can be the very important indicator of the problem. Much like second guessing at this end. Hope it does not turn out to be something serious. If you ran without oil pressure for instance and could post the suspected time it will give other posters of more experience a better ideal. If you caught it right away post that as well. when you say low on oil you could just mean a couple of quarts for example so it probably was not an actual contributor to this problem. On the otherhand if you were way low and oil pressure was not there for awhile it changes the whole picture perhaps. I guess that is even more important information to post even than the present noise sounds. Is your current oil pressure as good as before the low oil episode? Does the noise change at all as the oil heats up at idle? If you think it is in the valve train a really good inspection of it is in order. That would give you a chance to checkout the timing chain tension and rails as well.