Many cartomizers and atomizers give off a metal taste in the initial use. The primer used is sometimes used in extracting the mesh used in attys and can contain a metal taste but after broken in or blowed out, the metal taste shouldn't continue. There has been reports of some CE2 earlier models that never lost it entirely - I'm not familiar with the phoenix though. You should check other
reviews. The VG or PG shouldn't affect anything metalic - the VG should be diluted with H2O for blending. Burning tastes are almost always a result of gunk building up around the coil (or filler or sock burning in cartos). A good cleaning would be in order. It may also be the flavoring - either some sugar or oils used in flavoring will do it. (not recommended but some vendors still use those in flavorings)