sprinter faults...any ideas?

i have an 01 311 cdi sprinter with a couple of faults, the drivers side rear caliper is binding...even though i have fitted a new caliper,would it be the flexi hose or the load valve on the back??,also i have a strange noise from the air intake into the airbox,its as though the engine is sucking in too much air there is also a lack of power and a diesel smell(which burns eyes)in the exhaust smoke,changed turbo,boost valve cleaned pipes etc with no air leaks.......any ideas???????

Thanks in advance for any info or answers.