#8 Injector Low Contribution Rate - Chase the Issue or Ignore it?
So I picked up my 01 with super low miles from a construction company that I work for. It had been sitting since 08. I own a auto shop on the side so we brought it in changed all the fluids, rebuild the front end, change the filters (trans, oil, fuel), etc. In the process of going over the rig we tested the injectors and found the contribution rate on #8 to be low. It wasn't setting the CEL off but there was a code in the system. I took the truck and ran it for about 1,000 miles to get some fresh fuel through the system as well as some fuel additive (I think it was Power Service Diesel clean). After the 1,000 miles of running we retested the injector and were still getting low contribution rate on #8. So we replaced the injector with a factory replacement. After injector replacement we are still getting low contribution rate on #8.
My question is does this need to be something I worry about and keep chasing? I've read up a bit about the fuel system and am aware that the #8 is at the end of the line and can get a bit starved by the other injectors ahead of it in the line. The truck seems to run just fine at start up, idle, cruizing and WOT and I'm averaging 15 MPG on the highway at 70-75 which seems reasonable for my tires and the size of the truck.
Any advice as to whether I chase or forget about this issue / non issue? If I do keep chasing where should I look next?