So my girl's 2001 Ford Escape, 4 cylinder, 4wd Escape stalls out and will not start back up when the weather gets warm outside. During the winter or colder weeks (60 degrees or below) it doesn't have any problems. Im clueless, I did a mild tune up on it. Spark plugs, plug wires, and air filter and it still has this problem. Especially now that its staying warm outside now. Any sugestions?

~Brett