More than likely you are not feeding him properly. Are you discarding all but 1/4 cup or less before you feed? How much flour are you feeding? I know it is hard to throw out most of the old starter, but you must in order to keep your starter healthy. You can use the discards in pancakes, quick breads, etc. if you can't bear to throw it away. If you keep a very small amount of old starter, then you won't be throwing out very much. I generally only save 2 T. and then feed it about 1/4 to 1/3 cup of flour, leave it at room temp. for an hour and then put in the fridge. When I am ready to bake with it again I give it a larger feeding so I have enough for my recipe. Oh, and the vinegar serves no purpose now that the starter is active. It's purpose in the beginning is to help lower the pH to get things going. 

I use Peter Reinhart's method for starter.  One thing PR is emphatic about is that the starter has to be at least doubled when feeding.  e.g. if you have 1# of starter you have to feed it one pound combination of water and flour.  The starter can be tripled and quadrupled even. 

It's not necessary to throw starter away.....this is done at home because you would have huge amounts of starter if you didn't.  I bake once a week, so after baking, I have one pound of starter at 75% hydration left. I keep this in the fridge until the day before baking.  I feed the starter 9.2 oz flour and 6.8 oz water, which is one pound (@75% hydration).....I let this double at least on the counter, punch it down, and put in the refrigerator until the next day or two days later when I use it.  Which gives me fresh starter to bake with. 

After measuring my starter for my formula, and measuring a pound for my keeper....there is left over starter.  Using baker's math, figure how much flour and water is in the excess starter.  Subtract the water and flour totals from one of your yeasted bread totals, and add the starter to this dough using the formula's amounts for the other ingredients....use the same amount of instant yeast that the formula calls fall.....I usually use my left over starter for foccacia....

There! no starter to throw away....put your keeper in the fridge until next week, or a day before baking.....and voila!   I feed my starter once a week even if I'm not baking, which rarely happens....but then, I have to throw away some starter because it would be to massive.  I've been keeping my starter for months like this, and it is very healthy.

Tao, as the originator of this formula, may I offer you some tips? It's really never a good idea to add vinegar to your starter, especially a sluggish one like you're describing. I am aware that there are versions of the original forumula on the internet that suggest adding a 1/4 tsp vinegar when the new starter is slow to develop, but what I found in my research is that 1/4 tsp isn't enough to have any real impact on the pH, and more is strongly inhibitory to yeast. Simply stated, a small amount may not hurt things, but it won't help either, and larger amounts can absolutely stop it in its tracks. This is why the formula calls for pineapple juice rather than vinegar in the first place. So, no more vinegar, okay?

Not having a sour smell does not mean the starter isn't sour. The best guage of sourness is your tongue. What does it taste like? Lactic acid doesn't have much, if any aroma, and so if there isn't much acetic acid present, it may not have a sour smell.

To get a sluggish starter rising again, you need to feed it more often. May I suggest that you bring it back out of the refrigerator and feed it twice a day until it is strong and healthy, before storing in the fridge. You don't have to be a slave---you can feed it and park it in the fridge to slow things down whenever you know you can't make the next feeding. Then get it back out and continue as soon as you are able. Just don't let it go hungry waiting for you.

P.S.  Welcome to TFL :-)

I don't mean to hijack the thread, but I've been reading so much on this subject that I'm going blind.  For anyone new to baking, I found this idiot proof (I have to have) explanation of percentages here:

http://www.artisanbakers.com/percentage.html

It explains forward and backward and for a novice baker it really helped me to understand the principle more clearly.

Carol

First off, thanks to again to everyone who commented.  Everything posted was very helpful.

I pulled Les back out of the fridge and started him back on a daily feeding.  He was really sluggish for most of the week, just languishing in the container and making a little hooch, but not much else.  I was almost ready to start over, when I came across Susan's "Well, I finally did!" post.  Intrigued by her mention of Reinhart's 1:3:4 ratio for refreshing starter and, figuring I had nothing to lose, I gave Les one last effort using this ratio to try to perk him up.

I walked out the next morning... and Les jumped up and asked to borrow the keys to my car!

Hyperbole aside, he had doubled in size over night, no hooch and he smelled good again.

This loaf is the result of the weeks effort.  There are too many variable, in my mind, for the ratio to be the definitive reason that my starter perked back up, but it seems to be the most likely factor.

That's a beauty of a boule. Wonderful crust and crumb!

Betty