Good at boulders, suck at routes

Compared to my friends I'm a little better than them on bouldering but I really suck at routes. I get pumped so quickly compared to them even though the moves are easy. The more overhang, the bigger the difference. I also feel my endurance is getting worse, any training suggestions? I don't want to lose my maximum strenght either because I like bouldering more than routes (wonder why..). I suppose climbing up and down routes and staying on the boulder wall for a long time would help. Maybe people are different genetically, or am I just poorly trained? My maximum strength and balance is pretty good.