i have a 2000 honda accord v6 4door the car runs smooth once i get it started but randomly the car wont start i gotta try it over and over and finally hit the gas for a while until it stays on. Recently its gotten worse now the engine starts shaking when i try to turn it on it looks like its gonna turn on then the engine shakes and shuts off all within seconds and then an awful sound like something dropped. i had the oil and the spark plugs change recently thinkin that was gonna fix it because the code my mechanic was getting was engine missfiring on all the cylinders (301,302,303,304,305,306) so he suggested spark plugs but no luck my check engine light is still on and it flashes when the start up problem happens.
please pitch me some ideas on what could be causing this and what to do to fix it im also getting (171 code oxygen sensor)

 

It would be nice to know what the actual code was.

"but randomly the car won't wanna start" Definition of Randomly? hot start, cold start?

There is a known problem with those engines flooding on a "warm" start; as in a short 4 block drive to the corner market.
IF the engine is already been warmed try holding the gas pedal 1/2 way when cranking to see if that helps your situation.
If you think the engine is indeed flooded hold the gas pedal all the way when cranking.
I have seen sometimes injectors leak down, but that would only flood the cylinder with the missfire code, and that problem MIGHT fit a "random" description.

 

codes are:
171 oxygen sensor
303 cylinder misfire 3,4,5,6

What i mean by randomly is when i leave my house in the morning it might start up or sometimes it wont. then on the other side i can be driving the car park it and shut it off to go in the store come right out boom it doesnt wanna start. so i guess i had it happen on a cold and a hot start.

thanks for the suggestiong ill try it