Frank,
It was going to be the last post but then I decided to perform anothe experiment and I want to tell you about it.
I analyzed the NOAA plugin scripts and found the lines that update the METAR.rwx file, so I disabled those lines. Apparently the plugin does not use them and seems to run fine, as a result I hav no METAR.rwx, only MAXMETAR.rwx.
So far so good,
José