Note that riding with narrower bars will not allow you to open up as much for breathing as before. As far as handling goes, you'll likely find that it will be twitchier and at first you might be prone to overcorrection. One of the position on the bike that matters is your reach. This is typically measured from the tip of the saddle to the centerline of the bars at the stem. Typically to keep yourself from changing position too radically, you would make sure you retain that reach. The other important measurement is your drop. Obviously trigonometry tells us that hypotenuse and angle will determine reach and drop so you have two variables to play with to determine the other two.

However, it sounds like you're trying to reduce the reach as well as reducing your drop. You may want to consult the the stem sizing chart from Habanero Cycles to determine an appropriate length and angle for your stem.



I generally go by the slightly corrected "shoulder width" method of sizing handlebar width. Many will tell you to size your bars such that the center-to-center (at the hoods) is equal to your shoulder width. I like mine a bit wider as it opens up my chest for better breathing so I drop a pair of bars across my shoulders to test fit which gives me an inside-to-inside fit and thus makes a center-to-center slightly wider (by the diameter of the bar) than my shoulder measurement. Obviously this is not really exact but it seems to work well for me. What you can do if you want a narrower width is to perform the same fit test and then drop down a few sizes.

My suggestion however would be to change one thing at a time. You may want to first change your stem before your handlebars as that's often cheaper. Then if you still feel too stretched out, try going to a narrower bar. BTW, have you had a proper bike fitting? You might want to give that a go first before you start tweaking. Constantly replacing components or randomly changing adjustments can get frustrating unless you have a good baseline from which to work with.