The French centre-back headed home a left-wing corner from Pilgrims' skipper Paul Wotton, only to see it disallowed for an apparent push.
Earlier, the inconsistent Taylor had waved away Argyle's first-half penalty appeals when Stoke defender Clint Hill wrapped his arm around Stevie Crawford.
Doumbe deserved the goal after a magnificent defensive performance in which he and Irish colleague Graham Coughlan kept Ade Akinbiyi and Gifton Noel-Williams quiet.
With the Stoke back-four equally parsimonious, chances were at a premium.
Akinbiyi spurned his only opportunity of the afternoon when he shot against Argyle goalkeeper Romain Larrieu's legs, and Wayne Thomas, making his 200th appearance for Stoke, blasted a volley over the bar when well positioned.
Midfielder Dave Brammer, Stoke's outstanding performer, extended Larrieu again in the second half with a low shot that was turned aside - but that was a rare opportunity for an injury-hit Stoke side that visibly wilted in the later stages.
Akinbiyi was lucky to stay on after Taylor went to book him and then remembered he had already shown him the yellow card and changed his mind.
Taylor was more decisive five minutes from time after Wotton's in-swinging corner was headed powerfully home by Doumbe, signalling for a push as the Argyle players celebrated what they thought was the winner.