D4204T Help! V50 2.0D, intermittent power loss - no fault codes

[JBetts]

It looks like my issue is sorted now, loss of power once every couple of days, either not able to pull away at lights and engine will not rev at all (well, takes about 30 seconds to slowly rev up and then clears itself) really concerning, wife would not even drive the car anymore after a few scares.
Removed and cleaned the ERG and throttle body, but no difference
Noted air running inside clear fuel pipe between filter and pump (lift of engine cover to see on 2.0D) but only when revving up the engine, tried a few fixes including replace filter O ring, but still no good, bypassed filter with the push fit connectors and air was gone, so filter housing at fault, removed and inspected, found a 0.5 mm step in the housing from manufacture that could cause the O ring to snag and get an uneven friction when being clamped with lid, so filed down and sanded smooth + ensure O ring was removed and greased on all of surface area, refitted pumped out air with my Halford hand pump thingy then turned over and again pumped on the return pipe (that's for those that have not worked on diesels before) fired up and no air, that was 4 weeks ago now and the car is like a rocket, with not even a murmur, like a new car again and pleasure to drive, suspect this was an issue for at least a year and I just had not noticed it until it got very bad. hope this is of help to some body out there.