Very strange,
My truck is only 2 weeks old. Been to the dealer now 3 times. I had to leave it today because every time I start the car for the first 15 minutes, every time I hit about 2000 rpms, I hear this god awfull rattle/grinding sound from the engine/underneath area.
Thank god it made the noise when I had the advisor in the car with me today and I raised hell.

At least they gave me a rental, after a little bit of yelling.
Anyone else experience any kind of noise like this??

It does seem to go away after running for a little while.

found the problem today, shield for cat converter is bad and loose. can't replace just the shield though, had to order one new cat assembly.
Another trip back the dealer next week for install.
omg, i hope thats it for the problems.lol

Hey HEAT!

Don't know if this is the same thing that is happening to me BUT it sure sounds like it! I have noticed this when I started the Mada as well....but I only heard it RIGHT when the engine came on (so the noise didn't last long).
ANYway, in my case it is the air conditioner...I have noticed that if I left the air on from the day before and start the car I hear that awful noise. The funny thing is that the HIGHER the air is on the louder the noise! So, RIGHT before I start the truck I make sure the air is off....or on low.