I just thought of one more thing. Did you clean the tank out completely before using it? If you didn't, you should as there may be residue from the machining process left in there that gives a yucky taste. A 10-15 minute soak in vinegar followed by a soak in hot water (after disassembling everything including the screws) will remedy that.
Some people vape a few tanks through to get it out but I , personally, can't stand that. Fortunately the place that makes my primary atties puts everything through a UC bath before assembling so I can straight from tearing open packaging to enjoying a fresh vape.