08 accord ex-v6 auto. engine vibration @ idle in park or (gear at stop) when engine is cold to warm until it fully warms. dealer states it's normal. dealer showed me another accord with similar shake.??? it has 8k miles, purchased it used month ago. i didn't know about the vibration until the next day when i started. chevy, cadillac, or any other cars with flex engine switching (8 to 6 to 4 or 6 to 4 to 3) that i've driven have never had this problem what's with honda?

I don't know if this will help. Had a similar problem with a 99 Blazer.
Would drop to between 300 and 500 rpm at stop signs and red lights, would stall and shake.
Did all the same checks, replaced mass air flow sensor, replaced cam sensor, cleaned the fuel injectors but the problem was still there.
Replaced both #1 and #2 O2 sensors in the exhaust pipes and now the vehicle runs fine. The idle is back to a steady 750 rpm in all stopping conditions. The Mass air flow sensor and Cam position sensor get information from the O2 sensors.

full power is only achieved when the engine is fully warm(operating temp).so if you accelerate more than, say, a third of the gas pedal,the car will feel sluggish.
this is more apparent when first starting the car in the morning in winter.almost like the car is going to stall.
most wear in the engine is leaving it to idle when cold you should always drive the car straight away from cold.then when hot turn on the a/c if required....

check engine and gear box mountings

Check for vacuum hose leaks or component clogs. You can use vacuum pressure tester.
or turn the idle screw down.

run scanner for trouble codes, some auto parts stores will do this for free

The fast idle valve is inside the throttle body. Sometimes it backs out and needs turned back in (it's threaded). This will cause the loping idle.

Get transmission filter changed with new fluid. Honda does not recommend transmission flushing.

I need to get a clear mental picture of what exactly is happening.

With this said, you stated that the car "runs fine" until warmed up.

Q: When you start the car when cold it idles fine?
Q: If you allow the car to idle until "fully" warmed does the car stall?
Q: As the car begins to warm up, Does the RPM fluctuate abnormally?
Q: Does the car Only stall when you press on the gas pedal or does it stall just sitting and idling in addition to pressing the gas pedal?
Q: If you can drive it while cold does the car stall during acceleration when warm or only at Stop Signs / Lights?
Q: If you wait 20min or so, can you start the car again?
Q: How many miles are on the car?

The problem is the torque converter solenoid. I had it happen on my 94 Cavalier a few years back and was a cheap fix at the local car mechanic. What happens is the transmission warms up and hits a certain speed where the solenoid engages, but then it sticks and won't disengage until it cools down sufficiently. When it sticks, it causes the car to shake when slowing down and will snub out the engine if you come to a stop.

change the gear box and expensive for u haha cause its auto mines manul

change plugs