Sheila and the Brainstem.

Somewhere in the American southwest, Taz, a nutty visionary, has temporarily misplaced the wizened dried-out Brainstem he found in a mysterious subterranean world -- which he believes is the key to immortality. Three rebellious punks, Sean, Head and Billy Dork, unknowingly steal it in the course of a convenience store robbery believing it to be a stick of beef jerky. Newlyweds Bruce and Sheila have the misfortune to stumble into the confrontation between Taz and the Punks. The punks kidnap Sheila as a hostage, Taz kidnaps Bruce as his hostage; the bizarre chase is on! The two "teams" race across a landscape of identical convenience stores, housing developments, and rampant consumerism.