Rattling sound from inside the engine, black smoke, no power.

If it is a 6 cylinder inline then catalyst is plugging up a easy test would be to remove a oxygen sensor and see if power returns to normal. V-8 models have 2 types of manifolds plastic and metal the metal ones have a plate bolted to the bottom which the gasket splits and sucks in engine oil causing all sorts of drive ability issues the plastic versions more trouble free but PCV ventilation system can cause smoking

Diesel engine? Black smoke = your injection pump is broke

seems like you are having turbocharger problems the rattling may be coming from your turbocharger as well as the smoke may be the oil which the turbo its burning as it touches your hot manifold, hope this helps you .

White smoke is coolant.
Black smoke is oil
Blue smoke is excessive fuel

That sounds like engine flooding, getting too much gas. Have electric choke checked for one but black smoke with drop in power must be too much gas at times.

blue smoke = burning oil

however, your symptoms sound more like black smoke which means you are running rich.... this could be caused by leaking injectors

personally it sounds like you have multiple unrelated concerns... which do you want to address first

sounds like your cat converter has broken up and is now plugging you exaust.turn off engine crawl under truck and bang on cat converter with piece of wood if it rattles cat is bad. but dont just replace it because something caused it to go bad,number one reason of broken cat is a hard missfire so if runs rough fix that first.number two reason is to rich fuel mixture is it burns the eyes smells bad or has black soot or smoke coming out the tailpipe fix that first also.

Your getting backfires? hmm interesting. Seems like your engine is getting flooded and either purging it out of the exhaust or burning it all at once or both (backfire). Sounds like a leaky engine valve to me.There again the bluish smoke indicates to me thatyou are leaking oil somewhere- bad rings or head gasket maybe, which could cause a loss of compression which could also cause your problems.That rattling from the left/rear side sounds like a bad muffler try kicking the muffler (not hard though) next time you walk by it.

Sounds as if you are running extremely lean.Has EGR been bypassed maybe?
What is fuel pressure,on that vehicle the fuel pressure regulator may be adjustable.Some of these had an allen screw inside the vacuum port where you could richen the mixture some.Also try backing down on the timing a few degrees.

This could be as simple as the EGR (exhaust gas recycling) valve stuck open. This valve is supposed to open at a specific time, recycling the exhaust gasses back through the engine. If they stick open, the engine is not getting the correct air mixture to burn the fuel efficently, causing black smoke and lack of power. Have the garage remove and blank off this valve. If it runs ok, then a new EGR is needed.

TL