Can't find the clatter

[stealthguitar]

01 prism lsi 77,000 miles. I am getting a clattering sound coming from the front end only in a certain RPM range around 2600 to 3100 rpm. Not during idol or really higher or lower than that. Going up a steep hill will exaggerate this.
Here's what I've tried so far
Bottle of techron
Tank of premium
Changed all the plugs and they looked fine
No EGR valve and no timing belt (timing chain under there). I've been researching this like crazy and can't come up with the solution. Suggestions please!

Thank you

[stealthguitar]

Could it be an exhaust problem? Anyone have any ideas?

[Mr500CM]

Originally Posted by stealthguitar

01 prism lsi 77,000 miles. I am getting a clattering sound coming from the front end only in a certain RPM range around 2600 to 3100 rpm. Not during idol or really higher or lower than that. Going up a steep hill will exaggerate this.
Here's what I've tried so far
Bottle of techron
Tank of premium
Changed all the plugs and they looked fine
No EGR valve and no timing belt (timing chain under there). I've been researching this like crazy and can't come up with the solution. Suggestions please!

Thank you

Could be either a heat shield on the cat or a ideler pully thats shot.

[n1ckml007]

heat shield on the cat

I just had mine pulled off, as the bolts holes rusted out.