I put some redex cleaning solution in the diesel tank to clear the engine out but seems to have made it worse cos still coughing out loads of black smoke when revving plus making the car jumpy when going down the carriageway anybody know how to make it better??

blocked fuel filter,clogged egr valve,inlet manifold clogged up could be anything have u tried blanking egr valve with stainless blanking plate??..any split hoses??

Sounds like an EGR issue, that tends to be something you can fix with a blanking plate.

as stated by both members above ^^^^^^^^^^^ ditto.................... on a lighter note could also try covonia cough medicine with clout haha

Maybe the redex has moved some cack and blocked the fuel filter more, when was the last time the filter was changed, possible cheap option to start with.

Redex also as a cetane booster (similar to an octane booster in petrol ) and if the car is already running rich the higher cetane would make it worse

As suggested, changing the fuel filter may help (best with genuine Ford or "premium"/ well known brand, some cheap pattern fuel filters can cause problems (like restrict fuel flow, or get clogged up quicker)

Thats good advice about the EGR valve blanking plate, if you have the electronic valve, it can be expensive to replace, and seems to need replaced all too often, if its Euro 4 you may get the EML coming on intermittently , this can be reset with a code reader - some owners prefer to run their Euro4 mk3 Mondeos like that, solid stainless plates are best - ones with holes are literally a waste of time

Another problem area not covered is the VNT mech coking up and sticking

A burst boost hose (the one on the left between the intercooler and manifold seems to go 1st, split can be hard to spot without taking it off) can cause a rick mixture

As can a clogged air filter - a cheap thing to sort, at about a £5 a pop, i change mine every 6 months/ 6k (Ford recommends to long an interval IMO )

What fuel are you using? There is a potential problem with 'high bio' fuels (beyond 7%) and that could come into play with either home made biofuel, or the commercially available variants.