2003 Ford Escape Ticking noise in the egine.

Engine has a ticking noise coming from the top of the engine. Does not make the noise untile it warms up. I took it to the Ford Dealer and they had a hard time figuring out what it was. They called thre coorporate office and decided the cam needed adjusted or tightened. They said it was repaired but the ticking noise it was making now was fuel injectors. Well a few days later it still makes the same ticking noise it was making before and it's not the fuel injectors. Any suggfestions on what the noise may be and how to repaire this problem?
Thanks, GLW