Rattle at 2000RPM

just bought a 99 Grand Prix GT 115,000KMS on it

When the engine is under load and is warm, EVERY time (doesnt matter what gear or speed) you hit 2000RPM, there is a 1 - 1.5 sec rattle. If your good with the pedal and can keep it VERY still at 2000RPM, you can get the rattle to stay longer

I am currently taking an automotive course and asked my teacher what he thought it could be. I also researched online, and both pointed towards motor mounts. I took it into the dealership on Friday, and they said it was a loose heatshield by the resonator. Well they tightened it and its still doing it. I'm going back but not till next friday

any ideas what it could be? anyone ever have sometthing similar?

With the brakes (and e-brake) firmly applied and the car in drive, have a friend apply the gas while you watch the engine. If the mounts are failing, you will notice the engine drop considerably under load.

Upper mounts are about an hour and a half job. Lower mount is not a do-it-yourself job since it requires lifting the engine somewhat to replace. Just did my upper mounts on Friday with MSP poly mounts ($69.99 at 3800performance.com). Had the lower mount done last week (cost $175.50/labor and $106.51/parts)

well I wont have to pay for this one, seeing as I brought it to them on friday and they didn't fix it (I wasnt charge either), I'm, just brining it back next week and have the tech drive with me so I can show him wtf I'm talking about. Because clearly they didnt hear it the first time

just wanted to know if anyone has ever had this issue before

one thing it could be, i know mine is doing it. is the timing chain rubbing up against one of the guides. i get the same noise when under load. kind of a rattle. or almost sounds like piston slap.

shit sounds expensive. Wow they better not charge me for this shit, I'll be uber pissed!

yea mine is going to cost roughly $640US and that is just labor ad probably another couple hundred for parts.