2000 Jimmy rattling while accelerating

To me, if it is a pinging noise I would look at the engine, but, if it is a rattling noise, I would first look at the heat shield of the exhaust manifold by the spark plugs, it may have rusted away or the bolts did, feel around with your hands on the driver side bank and see if something is loose, I had the same problem on the right bank, and thats all it was.

Thanks for such a quick response, guys. For anyone else wanting to offer advice, I've heard pinging/knocking before, and this is not the same. My guess is the solution will be something like the heatshield steelwheels is talking about.

I'll give that a try tonight and update.

Alright, checked the heat shields on the exhaust manifold. They both felt secured to me. The bolts were definately rusty, though. I didn't take the engine apart or anything, I just snaked my arm down into it. I don't know exactly what I should be feeling for, but I figured if only one side was loose, they should feel different. Both felt pretty secured though.

Any other ideas or advice for the heat shields?

Dont know how loud the rattle is, it may still be what I mentioned, just cause they "feel" tight, doesnt meen they are, especially if bolts are rusty, in a quiet area, no noise around, tap around under the hood with a finger or something small, could be anything, but start on the driver side where you think it is, like if yours has it, it may have a protection cover or sleeve on steering shaft that is loose, and look laso at the brake dust shield on the rotor behind the tire, flywheel inspection cover underneath on tranny, re check converter and muffler shields again, driveshaft(maybe you picked up something)this can take some time to locate, or maybe you will get lucky and it will be quick.