By David Lawder and Andrea Shalal WASHINGTON (Reuters) -U.S. Treasury Secretary Scott Bessent's pledge of "large and forceful" actions to stabilize Argentina's wobbling currency by using a 91-year-old U.S. crisis fund could help the peso find its footing, at least for a while. Bessent's backstop for Argentina with Treasury's occasionally used $219.5 billion Exchange Stabilization Fund sent the peso and other Argentine assets soaring after major losses last week. But he said decisions on any U.S. interven ...