wgat will cause engine to smoke exsessively, lack of power, and turbo seems?

what a pain in the ass..... just had a full service,,, cambelt and water pump changed.... now the van is low powered, pours with smoke from the ass end, had a new EGR valve...... been told poss split in turbo pipe.... however there are 2, one is steel, the other is rubber..... any suggestions.... ps, if i been gassin you all out.... SORRY!!