Too much air or not enough fuel check the easy stuff first vacuum leaks check every vacuum line and it’s connections replace anything that is questionable I hate to say that it can be a multitude of things because nobody wants to hear that and I don’t want to give you a long list of everything that could cause it because it’s frustrating and overwhelming replacing vacuum lines is cheap and simple and it’s probably the the most common cause I’ve dealt with it for years in mine that’s why I’m also here haha mine idled rough for awhile and it blew a spark plug so I replaced it and the coil and the rough idle is gone