Loud knocking when im in it
 

I have an early 1991 d350. I have always ahd a problem at idle with a thin haze of blueish smoke and the strongest diesel smell. To the point where you get sick and your eyes are watering. Once back on the throttle it goes away 100%, and doesnt return until left at idle for a min or 2. I OD'ed on cleaner and it seemed to clear most of it up. Anyways. I recently did a bunch of mods, which included a FP guage, both new banjo's,AFC foot ground off, Pin ground, 366 spring installed, and fuel screw buried. I also have 4" full exhaust, BHAF, and many other guages.

Today after finishing up, I drove to work. Everything was good except when I get on it, under load say around 2300 rpm and above it starts this loud annoying knocking sound. I never heard it before I did any work this last time. With the clutch in, its quiet, at cruise its quiet, and at the point where I defuel with the 366 spring, its quiet. I had bumped the timing a few months ago, and reset the valves at the same time(1st time valves set, 140k, none really out of spec)

My fuel pressure pre-filter is 3-4 psi, and as low as 1.5 when cold, so i know thats out of spec(new LP on way) My question to the experienced, is does this sound like an injector knock? Its pretty loud, and my wife even asked if the truck was gonna come apart [whistle] I know I have an broken exhaust bolt at the rear port, but i cant feel any type of exhaust leak

Any thoughts? All other guages are in spec. and noise only heard under hard throttle

Considering all the mods and the symptoms, it is a good time to invest in either new injectors or an injector rebuild.

Yeah, I would try new injectors, or at the very least get the old ones redone.