Misfiring problem

[johnappleby]

Hi,

I've had an ongoing misfiring problem for a while - would welcome some advice.

The engine codes are P0300 and P0306 - misfiring, and misfiring in cylinder 6. First, we replaced the spark plugs and then, the coil pack on cylinder 6. We've flushed through some injector cleaner.

MAF and Air Filter were replaced some months back.

There are a few things which are curious:

- It only happens below 2000RPM and when you put your foot down. If you gently rev through 2000RPM and then put your foot down, there is no misfire.
- It is much worse in the wet.
- ABS and PSM lights come on sometimes (probably unrelated?)
- The CEL sometimes flashes for a few seconds and goes to solid. Then, it will turn off a day later.

I'm not really sure what the logical next step of things to replace is and would really appreciate any ideas.

Thanks!

John