Buy online or from a trusted shop and get a travel humidor to bring with you in your truck(otterbox, herf-a-dor, whatever). I wouldn't buy cigars from that shop again. It sounds like they are not properly storing them.

The sour taste and the splitting wrapper probably means that the cigars were too moist. The moisture in a cigar will expands as you smoke it. The more moisture there is the more it will expand, causing the delicate wrapper to split.

And I believe that an overly moist cigar can cause a sour taste, caused by the wet dense smoke produced.(I'm not sure about this, but I remember reading that somewhere).