2000 Grand Am 2.4L timing chain

Driving on freeway at 70 mph, lost power. Mechanic said it needs timing chain. Will it need anything else? Valves, etc?

Very well could have dinged a few valves. Not to expensive on parts but pricey for the labor to replace.

About the only way to tell is pull the head. Though you might be able to see the top of the valves are not sealing.
Or replace the chain and then check compression.

Then if its not holding, it'll all need tore down again.

Good Luck

Lost Power? Did it simply die or just get really weak?

Has the mechanic ripped the timing cover plate off?

If it did jump time chances are it kissed some valves..

Its also possible that the Timing chain tensioner may have failed...

This is the same engine as you have in your GA.... Not hard to view the chain assembly once the front cover is removed..
http://img.photobucket.com/albums/v294/Jr3800/Quad%204%20Twin%20Cam/DSC00012.jpg