My solution to this problem which I do is to rotate the bars very slightly so the hoods are raised. Make a pencil mark on the stem side of the clamp on the bars, slacken the bolts and just rotate the bars very slightly raising the hoods and then retighten the bolts, probably less than a milimetre may be sufficient. If it does not work try again, if it does work, job done. If things start to go pear shaped, just realign the pencil mark again with the clamp and try again.
The problem is usually caused by bending over too low and then raising your neck to see forward, by raising your neck just a "tad" is enough to sort it.
If it does not work after you have turned the bars so much that they do not look right, then it is time to flip the stem so it is angled upwards more.
Also check as well before doing any thing is ensure all the spacers are below the stem, and none above it, should not be with it being new, if any are above, move them to below the stem. this should also raise your head position.
A club rider had this problem a few months back, I told him just rotate the bars very slightly and it solved the problem immediatly without having to mess with the stem.