Havent had more then 15 mins to look into this since i just heard it and its getting dark out. I have a 2002 Chevy Blazer Xtreme. 115k miles. Auto.

Starting to hear a rattling noise, rattles for about 3 seconds when starting vehicle up. And when driving once every 5 mins it may rattle once or twice. Does not sound like its comeing from the motor. Sounds like its middle of the car. Any ideas or things to look for would be appreciated.

 

heat shield on cat? check the exhaust...that would be about the middle of the cab.

 

skid plates? exhaust uhh check your drive shaft for play also

 

I'll jack it up after work tomorrow if I have time. It's not a constant rattle either. Just last about 5 seconds here and there

 

Along with no sel on. No reduction in acceleration. No rattling from
Park to drive..drive to park. I'm hoping it's a minor fix

 

it might be something small like your skid plates if you have any or your bushings on the front suspension

 

Don't believe there are any skid plates on. Along with on my way to work I noticed it only rattles right around 1500 rpms. If it's 1400 or 1600 no noise at all. If that helps at all

 

Mine made some rattle noises from about center of vehicle turned out to be inside of cat. Hope it helps

 

Jacked it up, let it idle, and of course cant hear the rattling, take it off the jacks, drive it, and there it is. So no luck today trying to hear where its comeing from, gonna have to let it sit cold and trial and error it till i spot it.
How much was it to replace the cat?

 

I second the Cat. you may use a board or pry bar and put a slight pressure between the frame and the cat to see if it starts to rattle or stops rattling. In my case I did this to stop the rattle. Had to replace the cat something was loose on the inside. Don't recall the cost. My wife had it done while I was out of town.