Substitute Ben Kennedy’s spot kick 12 minutes from time consigned Cheltenham Town to their fourth defeat in succession on another frustrating afternoon at Whaddon Road.
Once again Gary Johnson’s men acquitted themselves well against a side vying for promotion, but not for the first time this season their hard work was undone by individual errors and a lack of composure in front of goal.
Stevenage quickly came out of the blocks and asked all the questions in the opening exchanges but they battled back to win a foothold in the game and produced plenty of openings over the course of the 90 minutes to get a precious goal or two, but they paid the price for not taking their chances.
They had one disallowed and struck the woodwork shortly after the break, but Chris Day was never really tested and as a result, the Robins have now gone three games without a goal.
Boro were too streetwise on the day, and won their chance from the spot after Jack Deaman had bundled over Kennedy who was going away from goal.
It was harsh, but that's the way it's going at the moment.
If there was one positive from the afternoon it’s that Hartlepool United, Carlisle United and Tranmere Rovers - the teams directly above the Robins at the foot of the table - all tasted defeat.
But that simply added to the frustration on the day, missing the chance to put pressure on those around them in the battle to avoid relegation.
So we’re down to five games to play, starting with the tricky trip to title contenders Wycombe Wanderers on Saturday.
Johnson marked his first match in charge at Whaddon Road with two changes, bringing in Joe Hanks and Mathieu Manset at the expense of Pablo Mills and Shaun Harrad, who dropped to the bench.
The Cheltenham goal lead a charmed life in the opening 15 minutes, with Stevenage creating five golden opportunities to take an early lead.
Charlie Lee was guilty of missing two chances, the first of which was a sitter from six yards.
Carson was called into a smart stop to prevent Dean Wells converting Simon Walton’s corner, who saw a header of his own cleared off the line by Joe Hanks.
Then Chris Whelpdale glanced one wide, meeting Dave Martin’s free-kick form the right with a stooping header.
At the other end, Cheltenham created a handful of chances to grab a goal against the run of play, but the ball was sent over the Bristol Street Motors Stand on three occasions, twice by Joe Hanks and once by Wes Burns.
They had a foothold in the game by the half-hour mark and had the ball in the back of the net after McDonald had run on to Manset’s threaded ball before curling one home, only for the assistant referee to chalk it off for offside.
Winter and McDonald found themselves in promising positions as the half progressed but couldn’t produce the quality to make the chances count.
Five minutes before the break McDonald again shook his marker to spring the offside trap and fashion a shooting opportunity, but this time his effort rolled tamely into the arms of Chris Day in goal for the visitors.
Braham-Barrett struck the upright from 25 yards in the opening seconds of the second half after cutting inside from the left on a purposeful run.
Then Will Packwood went close with a far post header, meeting Richards’ insignia from the right but that was the American’s last action of the game, who limped off with a muscle injury a moment later.
Deaman was sent on, joined later by Danny Haynes (for McDonald) and Shaun Harrad (Manset) as Johnson rolled the dice in the closing stages.
Cheltenham were indebted to Carson for a superb save with 20 minutes remaining to deny substitute Bruno Andrade, but with ten minutes to play came another decisive set back after another defensive error.
Stevenage broke down the left, but with the move seemingly running out of steam Deaman needlessly shoved Kennedy and the referee made no hesitation in pointing to the spot.
The confident substitute grabbed the ball for himself with Walton - the regular penalty taker - already withdrawn. After a short delay, he sent Carson the wrong way and found the bottom right corner to hand his side the lead with ten minutes to play.
There was more wastefulness in the closing stages,
Vaughan characterised the Robins’ afternoon by launching a volley out of the ground in injury time, from a great position 10 yards from goal, and Haynes was guilty of hestitation in front of goal to waste a final chance for an equaliser.
While at the other Deacon thundered one against the angle of the goal, and Kennedy squandered a one-on-one with Carson to seal the win, but in the end it was academic.
CHELTENHAM TOWN (4-2-3-1): Carson; Vaughan, Packwood (Deaman 53), Brown (c), Braham-Barrett; Hanks, Richards; Wynter, Manset (Harrad 73) , McDonald (Haynes 65); Burns. Subs not used: Gould (Gk), Kotwica, Sparrow, Berry.
STEVENAGE (4-4-2): Day; Bond, Wells, Dembele, Okimo; Whelpdale, Walton (c) (Andrade 65), Parrett, Martin (Deacon 76); Beardsley (Kennedy 57) , Lee. Subs not used: Beasant (Gk), McAllister, Pett, Conlon.
REFEREE: R Clark
ATTENDANCE: 2,858 (205 from Stevenage)