I have a rattling noise on my 2.8 mitsubhishi pajero 1997 model.the noise is at the front of the engine. i checked the timing chain and guides they look ok and tight.when i rev the noise get quiet but when iddling it rattles

SOURCE: 04 Endeavor rattling noise

I had the same problem! I crawled underneath the car and discovered that a heat shield on the exhaust header pipe was corroded and rattling against the exhaust pipe. (Before the muffler)
I removed the portion and clamps and solved the problem. Give it a try.

SOURCE: timing settings for 2.8 pajero auto 1996 chain

on the cam shaft there is a dowel it sopose to be up while crank shaft pulley is aline to 0 in most case damper rubber on crank shaft pulley shifts and cant get timming line up. in that case you get #1 piston up make sure its # 1, then on cam shaft put #1 int. and exh. lobes opposite so int. and exh. are close ,when engine turns exh. opens

SOURCE: terrible rattling noise from underside

Could just be the heat shield for ur exhaust. Looks like an aluminum pan between the floor and exhaust.

SOURCE: Mitsubishi Lancer ES '02 - Rattling noise in 1st gear...

I think you might need to ask someone to throttle up the car and you look underneath to try locating the rattling noise. Don't forget that this model runs the exaust pipe in front of the motor so it might be an exaust rattle as well??
Cheers

SOURCE: rattling noise during engine start up.. 2005 mitz galant 2.4l

Probably a heat shield. Often time the screws that hold the shields in place rust away causing the shield to rattle. After the exhaust heats up, the pipes and shield expand causing the shield to stop rattling until it cools down again later when the car has been sitting for a while. Usually you'll find shields under or around the catalytic converter and around the exhaust pipe nearest to the engine. Most folks would probably recommend you remove the shield and be done with it. That's your call. Just remember though, the shields are there for a reason. In particular, the shield under the catalytic converter is there to prevent the possibility of starting tall grass on fire in the event you had to pull off the road for example to fix a flat tire or something along those lines. It might be unlikely, but its definitely been known to happen. Let us know how it goes. Thanks.