I have a lope at idle, and a heavy miss under load. #6 cyl was a lower temp by 50*, so I changed the injector with a good, when last used, inj, 1yr ago. No help... I run a lot of wvo, I went 1000 mi and switched to diesel once. I am also running up to 50lbs boost. stock hg. I have ran a through a tank of diesel now and no change. My other 12v hg took a dump a yr ago 450k on it. It leaked water out side the block and from cyl to coolant. ARP studs and a decking fixed that. Could this be a cyl to cyl leak? How common is that? How can I diagnose this? Where should I start? I need this truck daily.

 

start with a compression check then you can narrow it down more with a leak down test.