The Egyptian right winger started his sixth successive league game with the Black Cats, whom he joined on a season-long loan from ENPPI.
He played on the right side of a four-man midfield that also featured Jordan Henderson, Lee Cattermole and Steed Malbranque.
He was lively in the first half, with his pace and acceleration causing Liverpool defense constant problems.
But it was Liverpool who opened the scoring as early as the fifth minute in a bizarre fashion.
Sunderland's Michael Turner apparently intended to let goalkeeper Simon Mignolet take a free kick in their own half when he back-heeled the ball towards him.
But the referee ruled that Turner had already taken the set piece, allowing Fernando Torres to gather the loose ball and square to Dirk Kuyt for an easy tap in.
Sunderland were given a chance to equalize when they were awarded a penalty on 25 minutes after Liverpool midfielder Christian Poulsen handled a cross from Elmohamady inside the area.
In-form striker Darren Bent stepped up to convert the spot kick and silence the home fans.
The visitors further stunned the crowd three minutes after the restart when Bent headed home an inch-perfect cross from right-back Nedum Onuoha.
Elmohamady had a quiet second half as Sunderland sat back in an attempt to preserve their one-goal lead.
However, Steven Gerrard drew Liverpool level in the 64th minute when he nodded in a Torres cross which got a slight deflection off Turner.
Sunderland, who lie tenth in the league table with seven points from six games, withstood a late Liverpool pressure to secure a share of spoils.