Argyle's youngsters could be excused wondering how they had lost this EFL Youth Allilance fixture, after twice taking the lead in Bristol.
The Pilgrims went ahead in the 10th minute, when a shot was saved by the Gas goalkeeper, only for Will Jenkins-Davies to follow up and slot the ball home from eight yards.
Argyle remained on top for the rest of the half, creating enough chances to have gone in at the break leading by a larger margin.
They were made to pay for not extending their lead just five minutes into the second period, as the Gas levelled with an unmarked header from a corner.
The young Pilgrims restored their lead on the hour, as Rhys Shirley broke down the left flank to put in Jamal Salawu, who calmly found the corner of the goal from the edge of the area.
The Gas required just five minutes to restore parity, as Argyle failed to clear their lines, leaving a striker to fire home for the edge of the six yard box.
Argyle had a great opportunity to restore their lead, two minutes later, but defender Brandon Pursall placed a free header over the bar from a corner.
In line with the theme of the match, Argyle paid the price for that opportunity spurned, as a wide free-kick saw the Gas score with a glancing header.
Although the Greens piled on the pressure, they could not find a way through the home defence again.
Argyle: Tyler Coombes, Jeremiah Medine, Ali Mansaray, Ethan Mitchell, Brandon Pursall, Jamal Salawu (Charlie Miller 65), Carlo Garside, Angel Waruih, Will Jenkins-Davies, Rhys Shirley, Oscar Massey (Oscar Rutherford 55). Substitutes not used: Lewis Moyle, Oscar Halls, Jeffery Forkuo.