A new noise has started under the hood, on the passenger side. There's a metal rattle sound that sometimes happens when I accelerate from a dead stop at an intersection. Any idea what it could be?

99 XJ Classic

 

With the engine running, crawl under the Jeep and find out.
Something gotta be loose....might be flexplate bolts.

Search "flexplate" on CF or "jeep noise" on youtube.

 

Motor mount?

 

is it a squeaky rattle sound and a little choppy almost?

 

thanks for all the responses. i wouldn't say it was squeaky. it was kind of clanky

 

Sounds like a motor mount to me. Check the passenger side mount

 

Thanks for the reply. I took a look, but can't see anything. it only happpend when i am quickly accelerating from a stop.

 

Check the motor mount.

 

Your exhaust could be slapping your crossmember.