This is interesting. I also have a 2004 Accord 3.0L V6 Automatic and I just experienced this same problem. I would encourage others who are having transmission to let others know. Does the transmission parts of The difference for me, though, is that the carks 'bucks' slight with downshifting. In addition, it doesn't appear to shift to higher gears during highway travel - thus the engine runs at higher than normal RPM (close to 3.5-4K RPM at around 55MPH). From memory, I'm guessing closer to 2.5k is normal.
HA ! Not funny - My transmission was rebuilt 4/2012 and then again in 4/2012 (didn't do the job correct the 1st time). I usually do 4-hr. weekend trips, because of no job and the price of gas, have cut those out. On 1/20/13 I did a trip to the shore. With the constant speed on the Interstate, after 74 miles, my D-light, check engine light, /\ light and TSC lights all came on. I pulled into AutoZone, who does a free diagnosis, P0717 & P0718 each with 3 codes (all the same), after I learned I could drive the car, I continued on to my 2 destinations, after the car sat for 2 hours, 2 of the lights went off, after sitting for 3 hours, only the check engine light remained, and after a pit stop the check engine light went off. I took the car to Honda on Monday night, they diagnosed it on Tuesday the only code that came up was P0717 which is a speed sensor, and the shaft that is inside the trans. Back to Lee Myles, who replaced the speed sensor; Now I have to pick up the car today, take a road trip to see if the lights come back on or not. If they do, the shaft is bad and they didn't replace it, overlooked it or ignored it having to be replaced in hopes the car would be out of warranty! This stinks - They take advantage of people who are not mechanics. I also found out HONDA had a ton of problems with their transmissions but the car needs to be in a certain VIN# for them to take it back. In addition, I read the 4 cyl have less problems than the 6 cyl which I have. Which brings me back to when I had a Chevy Impala (new) in the 70s went through one trans a year until I took them to court. They put a small transmission in a mid-size car which couldn't take the weight of the car (especially I lived in a hilly area), after the third trans, the Judge ordered them to put a new one in and prorated the 2nd one I had installed. They knew they were putting inferior parts in the cars and we the consumers get stuck footing the bill. Lenore07407 at gmail dot com