I'm going to get questioned on this I know so please ask all your questions. I need a solution fairly quickly.

I have an 03 Honda Accord V6 6speed.
The engine started misfiring on me and I ran a scan on it. It said that I was misfiring from cylinders 1-6 (P0301, P0302, P0303, P0304, P0305, P0306) plus a random misfire code (P0300)
I changed the spark plugs, coil on packs, cleaned the fuel injectors and nothing.
So I took it to a guy I know and he said that I need a knew engine, or rebuild that one due to 0 compression in cylinder 1, meaning a piston hit the valve and bent it, or something along those lines.
So that is exactly what I did. Bought a used engine with 91k miles on it and threw it in. Hooked everything up and boom, same exact codes.
My theory is that the ECU is messed up, highly unlikely.
The air-fuel ratio is off. I need to change out the Plenum Gasket and the intake manifold gasket as well. So those could be leaking. Doubt that thats the problem.
Or it could be the ECU needs to be reflashed?? Doesn't unplugging the negative cable for like days, reset the ECU??
Or it could the actual engine doing the same thing as the previous one and I'm back to square one again.
I'm running out of time and options.
If someone knows anything about this please reply. I need help!

 

Have you cleared the codes using a code reader yet?

What are the compression numbers?

Is the car driving fine, just have the codes....is the MIL?CEL flashing or just on?

What is the idle RPM? WHat happens if you unplug one coil at a time.....does each one change the idle?

 

I have cleared the codes and they keep coming back.
Have not checked the compression numbers.
Car drives fine but is definitely misfiring.
idles normally. right around 700-800
have not tried unplugging the coils.