Losing power.

Had on going problem for 20k miles. Peogeot diagnostics say one of 4 things, particulate filter...... Cat...... or the sensors to either item, and the particulate oil was low (which it is not.) have changed the sensors, no change.
Have washed out cat and Particulate filter twice.
These days the particulate filter light is on from the start and stays on.
Must keep the engine above 2k revs on the motorway or the system goes into limp mode.
More recently it has been losing power, very slow/wont pick up when under 2k revs.
So I looked at the EGR?? back of engine coming off the manifold (this was a suggestion from a mate that the EGR? Might be carboned up, it was clear as a bell, but I was surprised as to how hard it was to push the valve up??. Went to the other end of the steel delivery pipe, where it bolts onto the plastic 'Y' piece on the intercooler system, here it was 95% clogged with carbon/gunge, I thought this is the offender, all cleaned out and rebuilt..... no different?
So, when I had the plastic "Y' piece off looking into the butterfly valves I noticed the butterfly valve at the top was open and the one at the bottom was closed, the engine was cold at this stage so maybe this is supposed to be, or should it be open?

Any help would be usefull.

In antisipation

Thanks

Al.