My 2004 Camry with 125K miles makes a rattling noise from the right rear when started cold and driven for maybe 10 minutes then the noise seems mostly to go away. My local mechanic ran diagnostics and found no error codes. No check engine light is on. The spark plugs were replaced at 75K but not the ignition coils.
He removed the heat shield but that did not make a difference. Looking on line suggests that a loose honeycomb inside the converter could make a rattle noise.
Given this background, I wonder if the converter is responsible for ANOTHER problem where the engine runs rough and jerky at almost exactly 40mph and 60 mph. It’s not a shimmy or something felt through the steering wheel but an un-smooth running engine giving a herky-jerky feeling as you travel forward.
The mechanic did a test drive 40mph but did not experience the un-smooth problem.
Any suggestions are greatly apprciated.