Crusaders' win over Coleraine at Seaview wasn't enough to keep the title race alive after Cliftonville's last-gasp victory over Linfield at Solitude.
Coleraine keeper Greg Shannon saved a first-half Gary McCutcheon penalty.
Curtis Allen then appeared to have hammered Coleraine ahead but the goal was ruled out as a free-kick had already been awarded to them.
David Rainey and Matthew Snoddy scored for Crusaders on 80 and 83 with David Scullion replying on 85.
Crusaders' first-half penalty came after David Oglivy had fouled Declan Caddell but Shannon made a great save to deny McCutcheon.
The game's main controversy then came as Allen hammered the ball past Sean O'Neill but after initially being awarded, the goal was then disallowed by referee Alan Black after he had consulted with his other officials.
Black appeared to have blown for a jersey pull by Josh Robinson on Allen just as the Coleraine striker was firing to the net.
Nothing came from the resulting free-kick to add to the Coleraine frustration.
After half-time, Crues keeper O'Neill made a fine save to deny Allen before Rainey broke the deadlock 10 minutes from time after he nodded past Shannon.
Matthew Snoddy bundled in Crusaders' second goal three minutes later before Scullion's quick reply on 85.