I like the plan of an oil change and filter inside inspection. Before you isolate the engine from everything else, a quick check is to set the idle at about 1000 RPM. Use insulated pliers and pull up one plug wire at a time to disable it. Then move to the next one. If the noise goes away with wire out and comes back with it operating, you found the cylinder. If the noise stays, it's main bearings, or something outside the engine. (flex plate, accessories, torque converter).
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