I bought a 1996 Ranger 3.0, RWD about a month ago. 80k miles. 2 years ago the previous owner replaced a lot of parts under the hood after the truck had been sitting for a while. New radiator, spark plugs, wires, ignition coil, battery, alternator, just to name a few. It has the original engine and transmission.

The thing is, I've been hearing a metallic-like rattling sound when driving at high RPMs. I'll need to take my foot off the gas a bit to make it stop. I've read all around for what this might be. My heat shield seems secure, but just in case, I did put pipe clamps around it. Banging around with a mallet all over the exhaust and catalytic converter didn't reveal any sounds. Not sure if it's related, but the truck has a bit of a rough idle, nothing super bad, and a rough time accelerating, especially at lower RPMs. Speed maxes out around 75, which is fine for me, just takes a loooong time to get there. A smoke test revealed leaks at the IAC and EGR valves so I've replaced both. Also a slight leak at the throttle position sensor, but I haven't done anything with that yet. I cleaned the throttle body. I've tested two out of the three O2 sensors with a multimeter (the passenger side upstream one was too difficult to get to for me), and they appear to be ok. I've also run Seafoam through the fuel tank.

Not sure what else it could be. I hate to make a redundant post, as I know there are many like it, but with my anxiety I keep thinking the truck is going to fall apart every time it makes the sound, and I want to make this truck a reliable daily driver. Any help or suggestions what the noise could be?

Just to add, I've had a hard time finding a video showing predetonation sounds I can actually hear, but to my understanding it sounds a little like static. My sound only sounds metallic, and as I said earlier, plugs, wires, and coil were all replaced about 2yrs, 8k miles ago.

Best video I could get of the sound: https://drive.google.com/file/d/1UPK...w?usp=drivesdk

 

I can't hear anything in the video but I had a rattling sound at high RPMs. It was the timing chain rattling against the timing chain cover. It sounded just like a bike chain so there was no mistaking it. I had a coolant leak coming from the timing chain cover, so I had a new gasket put on and changed the timing chain while it was off. It accelerates and feels much better. Still some rattle when accelerating at high RPMs but it's less noticeable, and I assume normal.