How can I fix my car Vauxhall Vectra 1.9 CDTi 2007 150 bhp ?

Recently for the last couple of weeks my vehicle has been really sluggish, smoke through the exhaust, so had the EGR valve cleaned out but still the same problems so as advised used Forte advanced diesel treatment, made it worse that day but run smoothly for a couple of days & the same problems again. Had it in the garage most of the day yesterday for a diagnostic check & the following faults were detected on the Snap On computer, Intake Air System Leak, fault code P2279 Swirl Level Solenoid Circuit Malfunction, fault code P2075 these were the main faults. Can you give any advice on what the remedy would be please ?