After dominating the first half without scoring, Lincoln found themselves behind to a 51st minute screamer by midfielder Darren Garner.
Set up by winger Martin Phillips, Garner left fly with a left-foot 25-yarder which gave Lincoln goalkeeper Alan Marriott no chance.
Torquay hardly deserved to be ahead and they had a real escape ten minutes later.
Referee Steve Bratt ruled that defender Steve Woods had handled Ryan Amoo's shot, but Torquay keeper Nathan Abbey brilliantly parried Paul Mayo's penalty and Mark Stallard's follow-up.
Another key moment was an injury to in-form Torquay left-back Stevland Angus, who pulled his groin trying to shield the ball out for a goal kick.
Lincoln boss John Schofield made a key double-substitution in the 72nd minute, introducing Gritton and winger Ryan Semple and they pepped the City attack.
The referee had to go off injured ten minutes from time with fourth official Mike Mullarkey taking over.
When Mr Mullarkey added four minutes of stoppage-time, Lincoln were still behind.
But in the 91st minute Mayo nodded back Semple's right-wing cross at the far post and skipper Paul Morgan headed the equaliser.
And in the 94th minute Torquay failed to clear Amoo's corner, Jamie Forrester's first shot deflected into the path of Gritton and he made no mistake from point-blank range.