I have an 04 TSX 5 speed auto with 230,000 mi and it is extremely rough idling, especially in gear with my foot on the brake pedal, and even moreso under load from the AC. I’ve replaced the front vacuum operated motor mount with OEM and the other three with cheap mounts from eBay, I replaced the timing chains (including the balance shaft chain), spark plugs, repeatedly changed the tranny fluid and filter, cleaned the throttle body, inspected the MAP sensor which was nice and clean, and cleaned up ground terminals. The alternator, AC compressor, water pump, and PS pump, as well as the tensioner assembly have all been replaced. I’m truly at a loss. I tried the propane enrichment method of searching for a vacuum leak and didn’t seem to have one, and there are no CEL’s whatsoever. I’ve found countless threads describing this problem with these cars even at low mileage but I can’t find anyone who has spelled out a solution that fixed it. Many have described the dealer taking their money over and over only to give the car back with the same issue and needless new parts replaced.