Loss of power after injectors adjusted and overhead run

1996 Series 60 in a 2015 389 Glider with injectors which are larger than OEM (been in the motor since glider was new) and my last oil sample came back with fuel dilution in the oil. I put the rig in a Detroit repair shop that has done all my engine work the last 8+ years. The injectors were good but they adjusted them and I had the overhead run. I run the same loads on the same routes all the time and having driven this truck 660,000 miles I am very familiar with how this truck pulls. The day after I got it out of the shop in the hills I had to drop an extra gear pulling the hills and seem to have less throttle response loaded pulling the hills. I was curious if the injectors were set wrong where they aren’t allowing enough flow, the overhead wasn’t run correctly or now that the injectors are set correctly I won’t have as much throttle. I looked back at my previous oil samples and I have had fuel dilution in the past, but not enough to be critical.

 

When I said “the injectors were good” I implied that they checked them. Sorry for the confusion I will elaborate, they checked them and then set them to correct Detroit specs.

 

I will assume for argument sake that the shop that built this motor and did this work and has worked on it for the last 8 years is generally competent and worthy of my business. I am wondering why my power went down after the injectors were adjusted and the overhead was run.

 

Definitely doesn’t