Hello well 1hd-t is a life time survival engine
Following are the things you need to do on this motor and also you had forgot to mention the mileage of the vehicle.
Now let's come to your problems and there solutions
1: excessive black smoke
Now if I am not wrong this is an old engine and old engine tends to wear a little over the time if there is no engine oil consumption on higher mileage drain intervals like 7000+ kms then it's fine to smoke a little
If the acceleration is low along with low fuel mileage then you need some basic adjustment's which are following.
1: for general engine tuneup and diesel fuel system regeneration use liquid moly Diesel purge 1hd would take around 2-3 liters of it for fine tuneup. Disconnect the both induction and outlet pipes from main fuel supply line and dip them into the bottle and add the diesel purge in it start the engine and let it idle for minimum 20 minutes then add some more purge and now Rev the engine upto 1500 rpms and increase after 4-5 minutes continue until diesel purge runs out or is low.
Now reinstall the fuel lines again and start the engine again in normal diesel and let it idle for 20 more minutes after that disconnect the main turbo line and service the turbo by any good degrees error by spraying the fluid directly into the turbo (remember don't forget to disconnect the main turbo line or else you would end up damaging the engine by excessive fluid suction directly in the engine ) now the start tje engine and Rev it up turbo spool would throw out the debris and oily content and keep performing it until the turbo induction is clear of any debris and oily content let it dry out completly and reinstall the induction pipe again and start to drive the engine and enjoy the ride a bit of visual smoke is common on high mileage engine don't try to compensate it which ends up in lean mixtures resulting in more EGTS which will fast up the wear ratio by the pace of 10-30-50-70 . Donot adjust the injection timing on just hit and trial methods always use the dial gauge procedure and if it's not available then don't ever allow to touch the injection timing ever.