Hi and welcome! Buona sera!

I don't know if we have the same issue. On my case, the car seems to stop only to accelerate again when reaching 4000 rpm, like if somebody was pushing the brake, then releasing it. But when it finally gets passed 4000 rpm, the car does not have the same power.

I also don't have the complete loss of power.

On one of my latest posts you can see what are my next steps after having tried many things, but it is not going to be in the short term, as the car works fine apart from that and I have other things to address.

All what I did also served me to assess the health of the car and to learn mechanics. My issue was that I had to learn on the way and get the tools. If I had to do everything again today, I could do in one weekend what I did in 8 months.

I'm going to take it to the mechanic in a week.

He can swap the pump for not too expensive, and I can take the chance to do a full inspection of the area, piping, connectors, filters.

If it is not that, at least anything else I can do myself at home.

Make sure no hoses are bent, chaffed or collapsed, with the new pump, filter, fpr and if i remember well clean injectors you will have one system less to worry about

Thanks, it took me a lot of time to decide, thought I could do troubleshoot myself. This mechanic is specialized in Jags and looks honest.

During this little journey you have learned quite a lot and experience gained is priceless, after he'll find what is wrong you will be able to compare your assumptions and results to the professional and again it is priceless knowledge and finally from now on you won't feel uncomfortable fixing all minor stuff yourself.
So all gains and nothing lost, and let him suffer removal of the damned pump, it is no fun and only stuff you would learn is new forms of swear

First feedback from mechanic is that pump needs replacement, he says it makes a lot of noise, which I suspected but I couldn't compare to anything.

He says piping is slightly bent, but that that 100% is not producing my issue.

So this is where we are now. Now it makes me think, if somebody replaced the pump in the past, what the hell did they installed, to fail in so few time.

Otherwise he says my little red Jag drives impecable.

I hope we approach the end of this adventure.

So, yellow fuel, residues and slightly bent pipe.

He says the pipe he can straighten it up.

He also says the pump was no suited for the Jag.

Just in case, we won't celebrate yet, but we’re slowly heading toward the nearest champagne vendor

This guy is fast, I think maybe tomorrow he can install the pump and report back.