Gers looked to be cruising to the win thanks to a John Crawford own-goal but were stunned as substitute David Gray snatched a point for the visitors with a superb long-range drive.
As well as the disappointment of the draw, McCoist revealed he was angry with the performance of his side, who left the pitch to the sound of jeers from the home support.
The Gers boss said: “I was booing myself. I’m probably as angry as I’ve ever been as manager with that performance.
“Our overall performance was not good enough and our standard of finishing was probably worse.”
Asked if his players switching off was the problem, McCoist said: “I don’t know. But I tell you what, they better switch on kind of quick or they will be completely switched off.”