Car stalling problem

A few months ago my car started stalling. Always at speeds under 20mph, usually while slowing down to stop. The lights, and radio in my card would also dim, with the engine doing the same. Sounding much like it's reving then going down, then reving then going down till finally it dies, or keeps running. Never know when it will happens as it isn't a constant when I stop. After a month of it happening it went away completely. Just in the past week the problem has returned.

A friend of mine suggested it was the alternator and battery. Possibly the charge is just enough in the battery to keep it from just being dead. I am not sure how that would be possible due to the difference in time between the last time it happened and now.

And i'm a fool. 1993, SE V6