Got this annoying noise between 1600-2000 rpms. Sounds alot like the old valve flutter that we used to get with the older 289's and 302's. Tried several different brands and grades of gas and it makes no difference. Dealer said the cats were bad. At 34K is that possible? Truck runs great and I haven't noticed any loss of power. Could it be one of the numerous guards and /or heatshields on and around the engine and exhaust system? Any ideas???? I am at a loss to what this is, but what ever it is, I need to get it fixed before that warranty expires. Any help or ideas would be GREATLY appreciated. Anybody else have this kind of problem? BTW, I also posted this on the " Exhaust" section so that somebody who knows will see it and give me some ideas/ answers. Thank you all in advance for your help.... Max, where are you???

 

I vote for loose/bent heat shields at or around the cats. Wait for a 'free' morning---cool truck/exhaust and get underneath with a long screwdriver/poker and check it out.

Dan