Fuel knock sound

[Lonestar10]

I have a fuel knock sound starting or atleast audible around 1300 rpm and throttle of 50%+ started a little bit after overhaul.

Also when you first start truck engine will run smooth while building air as soon as it finishes building and air dryer blows off it will start acting like a gasser with an audible miss sound in exhaust note.

Also after going down road when parked hot will run smooth but for a while then after heatsoak wears off will start to stumble again.

Engines pulls smoothly no signs of miss but on takes offs from stop will throw more black smoke then it used to. Used to just be a little poof now it's a second or 2 haze (black in color).

Fuel mileage down used to actually have to purposely try to get below 6-6.5 now 5.3-6.3mpg is normal used to be 6.5-7.5 and really nice tailwind 8+

Here's what's been done with no changes.
Injectors, air compressor, overhead few times, turbo, ex back pressure sensor and cleaned tubing, pressure tested charge air system,

I bought a timing wedge kit so going to check for cam slip today or tomorrow.

Just wondering where else to look if cam hasn't slipped. Also head was new on overhaul also new rocker arms, crossheads

Isx 2350, 13sp, proper approved tune, 450/1650 ratings.