Pete you mention BLACK smoke this can only be too much fuel or not enough air!
The air/fuel ratio is wrong on this car
There are no codes & the car performs ok
Look harder for a split hose , take a step back to basics
Sometimes we get carried away with technology
Shame the injectors were changed before the oil !
Wouldn't of been my first move
Don't mean to be hard but we are all guilty of not thinking outside the box ,hope you sort it soon