I returned to this version of my code:

This should be a bug of word vba? I found that the loop/crash ocurrs only when theres a ^p^p at the end of the document.

Sub Limpa_texto()

Application.ScreenUpdating = False

ActiveDocument.Select

With Selection

With .Find

.Text = "^13{2}"
.Replacement.Text = "^13"
.Forward = True
.MatchWildcards = True
.Wrap = wdFindStop
.Execute

End With

Do While .Find.Found

.Find.Execute Replace:=wdReplaceAll

Loop

End With

Application.ScreenUpdating = True

End Sub

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Backup your original file before doing any modification.