Lost of power.

I've talked to someone about my issue already, but still losing power. On flat land truck runs fine. Freightliner Cascadia Detroit DD15. As soon as I start climbing hills I lose power. I get into Billings, MT to do my delivery then take it to I State freightliner. Takes them 2 effing dayz to diagnosis the issue. They finally say injector 2 is leaking. They recommend change all 6 injectors but my boss said change only the one that is leaking. So they change that only 1. We'll I finally get truck back 3 dayz later. I took it in Monday and just got the piece of garbage back today. Well, anyway, get back on I 90 head west and as soon as I get to hills the truck loses all power again. I was like wtf already!! My question here is, can my problem b because I didn't change out all 6 injectors?? Also my oil pressure seems way low. It's reading one line before the 50 mark on the psi gauge. Also I check oil on dip stick and it seems like mayb I have too much oil. Can that b the problem as well??

 

No. I have no turbo boost gauge.

 

Its a gd piece of crap and probably never get figured out. This the last effing time I have a freightliner.

 

I appreciate the advice Phil.