First-half goals from Neil Danns, Alan Lee and John Oster gave Palace a first win in five and left Argyle with just one victory from their last 16 games.
It left the Pilgrims teetering on the brink of the Championship relegation zone and heaped further pressure on manager Paul Sturrock, who has seen his side drop down the table from a position of fifth earlier in the season.
Sturrock made five changes to the side beaten 2-0 by bottom side Charlton at the weekend, but, despite plenty of effort, the end result was depressingly familiar.
After a bright start by the Pilgrims, Palace hit them with a fatal one-two.
First, Oster crossed for Danns to send a header looping back across the goal and over keeper Romain Larrieu's head.
Having lost 13 of 14 games after they had conceded the first goal, things did not look bright for Argyle, and so it proved seven minutes later.
Sean Scannell fired in a long-range shot that Larrieu touched on to a post, only for the ball to cannon back for Lee to score from what looked like a offside position.
Two minutes before half-time, Palace cleared an Argyle corner to Paul Ifill on halfway and his quick pass found Oster, who ran on to the ball and slammed a shot past Larrieu.
Any luck going was not with the Pilgrims, who had a stone-cold penalty call turned down by the referee after Jose Fonte clearly handled.
Argyle kept plugging away and were rewarded when defender Gary Sawyer scored their first league goal of the year on his 50th appearance for the club, firing home after Paul Gallagher's cross had been helped on by Karl Duguid.
Showing good spirit, Argyle came close to reducing the arrears further when Sawyer's header from Craig Noone's free-kick slid wide.