Fuji: Calm down
I found your post almost bit accusatory to be honest! I'm not some dodgy flyboy wideboy flying a dodgy plane around looking for trouble! I have two young kids for starters!
Lets not turn this into a slanging match, did I say I was flying the aircraft around knowing the engine pump (if it is that) was not 100%?
I would very much welcome any advice you and IO have to offer, seriously...perhaps if I PM you all the details? I'm interfacing with two AMOs to get the bottom of the problem, but its a tightrope between rational problem identification and repair and being ripped off chasing expensive geese. As I'm sure you both have experience of!