Posted this on the Q&A forum but not getting many replies, so I'll try here.

My 2003 5.9 Cummins HO is getting harder to start. I've owned it since new and it has 220,000 miles, about 90% highway, with about 20% of that towing. it's always had a stock tune. About two years I noticed it was getting a little slower to start. Instead of firing right off it might take six or seven revolutions to fire. Then a year ago it was taking significantly longer at times. I have gauges on it and the rail pressure was slow to build. It would fire as soon as it got to 1.5 kpsia. I replaced the relief valve since that is easy and no change. I then retorqued the cross tubes and that made it about 90% better. Now it's back to where it was. When I retorqued the cross tubes I was worried if it they had been leaking for some time that it might have cut a groove in the tubes or injector recess, so I'm not too surprised the problem came back.

So, the question is, what should I do now? Try retorquing the cross tubes again? Try new cross tubes? Or bite the bullet and replace the injectors along with the cross tubes? Once it builds 1.5kpsia it fires off quickly, no smoke, idles smooth and no change in fuel mileage. (I have been hand calculating the fuel mileage since it was new.)

I know that at 220,000 I'm on borrowed time on the original injectors, but if they don't need to be replaced, I can use the money elsewhere. If I do need injectors where is a good place to buy stock OEM injectors?

Any other advice? The batteries are new. (They aren't cheap either!)

Thanks for your help.