A cliché is a commonplace phrase or expressions. (A stereotyped character or a well-worn style can also be cliché.) So, yes, the idioms you're using can be clichés. Whether you need to avoid them or not depends upon the context. If you're using them in dialogue or in a first person narration, which tells the story in a specific character's voice, they may contribute to crafting a distinctive voice. In Raymond Carver's short story “Cathedral," the narrator and his wife use phrases like “hit the hay" and “did me in." The action centers on the wife's friend—a blind man—coming for a visit, an occasion that makes the narrator uncomfortable. These idioms work toward crafting character and help to reinforce the casual nature of the exchange.

Idioms don't need to be reserved only for a character's voice. A third person narrator might use them, too. Flannery O'Connor does this in her short story “Good Country People." The narrator uses phrases like “talk her head off" and describes one of the characters as physically present but “no longer there in spirit." This works in concert with other choices to craft a distinctive narrative voice.

Still, idioms can work against voice. You might use too many or they may accumulate in a way that dilutes the voice and makes it sound generic. In order to avoid this, only use idioms when they add something significant. Identify and consider each idiom. Is it a result of uninspired writing or is it contributing something specific? As you work through the idioms one by one you're bound to find many of them aren't productive. By paring those out or rewriting them, you'll be working toward a more distinctive voice.