The Black Cats failed to build on a first minute lead, given to them by Daryl Murphy, allowing the visitors to hit back and take an unlikely first-half lead, through David Norris and Barry Hayles and though Stephen Elliott headed a late equaliser, it was all in vain.
Substitute Nick Chadwick dispossessed Danny Collins to race clear and slide the ball past the advancing Ben Alnwick to the dismay of the Black Cats faithful, who are fast losing patience with the new Niall Quinn regime.
Sunderland took just 26 seconds to surge ahead, Murphy latching on to a Tommy Miller flick on to beat goalkeeper Luke McCormick with a low left-foot shot.
The lead was soon wiped out, however, Collins and Clive Clarke hesitating to cut out a through ball from Lee Hodges and allowing Norris to advance before beating Alnwick.
Collins missed a great chance to restore the home side's lead after Elliott knocked back a Dean Whitehead free-kick, heading wide, and the miss proved costly.
Kenny Cunningham was caught in possession on the left touchline by Hayles and when Alnwick raced from his line, the veteran striker shot goalwards and though Collins got his head to the ball, he was unable to prevent Argyle from going ahead.
Collins had a header from Liam Lawrence's corner headed off the line by Paul Connolly and at the other end Alnwick saved well from Hayles and Norris in quick succession.
Manager-chairman Quinn sent on Jon Stead and Chris Brown and the substitutions paid dividends when Elliott levelled the game at 2-2 with a 67th minute header and three minutes later McCormick pushed Brown's header against the bar.
But with both sides prepared to gamble for the victory, it was the Pilgrims who grabbed the winner through the determination of Chadwick eight minutes from time.