Shouldn't more muscle m make you winded faster?

Maybe. I've never thought about it. But I guess that's why marathon runners are so skinny. But fat would also make you get winded faster. And your muscles actually do the running, whereas fat does nothing. Any weight on you or in you would make you get winded faster, not just muscle. People can be muscly but still be good at running. Don't underestimate the strength of the heart. What would you suggest? Getting rid of muscle to get better at running would only make sense for a marathon runner. And you can't get rid of anything else, except fat. And that's generally part of the reason one runs - to get rid of fat. Stop making excuses and get on the treadmill.