Question:Would it be sin to worship in a congregation where the elders are not correct (I Corinthians 5:11)?
"Not correct" is too vague. Not correct by who's standard? If anyone is in sin, then what have you done to rescue them? To point fingers but to seek no restoration is to hate a brother. "If someone says, "I love God," and hates his brother, he is a liar; for he who does not love his brother whom he has seen, how can he love God whom he has not seen?" (I John 4:20).
Let's suppose that a congregation has a drunkard as an elder. There are steps that first need to be done to try and bring the man out of his sins. "Moreover if your brother sins against you, go and tell him his fault between you and him alone. If he hears you, you have gained your brother. But if he will not hear, take with you one or two more, that 'by the mouth of two or three witnesses every word may be established.' And if he refuses to hear them, tell it to the church. But if he refuses even to hear the church, let him be to you like a heathen and a tax collector" (Matthew 18:15-17). If it gets to the point that the congregation will not reject an member who is remains in his sin, then it will come to a point where you must decide whether you can continue worshiping there while keeping yourself separated from the sinner. What isn't an option is not worshiping with fellow Christians as a church.
What I've seen more often are people who decide they don't like a decision of the eldership or who get annoyed that others don't agree in every aspect with them. Rather than working at being of the same mind toward each other, the inability to work together becomes the reason for dividing. "Therefore if there is any consolation in Christ, if any comfort of love, if any fellowship of the Spirit, if any affection and mercy, fulfill my joy by being like-minded, having the same love, being of one accord, of one mind" (Philippians 2:1-2). It takes effort to be united and too few Christians are willing to put in the required work.