Do you have even a hint of a town? You probably already know this--Wuertemmberg is a state and "Mueller' (German for Miller) is a really common name since it derives from an occupation and almost every town had at least one miller. The name Lemuel may help eventually--at least you aren't looking for a Johann Mueller. I did try looking at the IGI and also geneanet.com, which I've sometimes found helpful for European searches, but came up with a blank for Lemuel Miller, Muller, or Mueller.