406 LX Power Loss

suffering from power loss and loss of revs on climbing hills and in low gears, also black smoke appearing out of exhaust any suggestions diesel pump recently overhauled. Any suggestions appreciated as to cause.

Managed to find solution to problem, simple really " blocked Catalytic pipe on exhaust" cheers any way all those out there now saying " I new that" BASTARDS it cost me 50 quid to find out. Use this bloody forum please.!!!!!!!!!!