step on it vs race

step on it is not a noun while race is a noun.

Word	Noun	Adjective	Verb	Adverb
step on it	No	No	Yes	No
race	Yes	No	Yes	No

As verbs, step on it and race are synonyms defined as:

Other synonyms of step on it include belt along, bucket along, cannonball along, hasten, hie, hotfoot, pelt along, rush, rush along, speed.

step on it (noun)	race (noun)
	a canal for a current of water
	a contest of speed
	any competition
	people who are believed to belong to the same genetic stock
	(biology) a taxonomic group that is a division of a species; usually arises as a consequence of geographical isolation within a species
	the flow of air that is driven backwards by an aircraft propeller

step on it (verb)	race (verb)
move hurridly	compete in a race
	move hurridly
	cause to move fast or to rush or race
	to work as fast as possible towards a goal, sometimes in competition with others