It may be a memory leak as you say but it is only occuring at KDFW
Well, more precisely, the memory leak is affecting only KDFW because, as I've said, it doesn't use standard runway lights like 99% of airports out there.
I have purchased almost all the FSDT airports plus GSX and they function fine
That doesn't mean much: every scenery is located in a different area so, any memory leak, that might even be related to surrounding scenery, can appear in different ways.
I will try uninstalling and reinstalling.
I don't think it makes any difference, other than the fact reinstalling would download all the most current Couatl support files so, if you weren't running their latest version already, it might fix some issues, so it's always worth being sure everything is updated.