Given the lurching regardless of how much fuel you're giving it, but only above 2200 rpm, that sounds fuel related. If the rpm only seems to exceed that expected at your particular speed when it lurches, that sounds like "slipping and catching" in the clutching mechanism, be it an automatic, hydrastatic or dry clutch. Yes, a vacuum leak will cause fuel draining back to the tank resulting in some air perhaps in the fuel feed or return system. I'm not expert in this, but I would think any air would work it's way through the system and the car would stop this behavior if you drove it for some time, say exceeding half an hour or so. As the previous forum member said, since it is the working on the fuel lines which immediately preceded the problem, this is where to determine if there is a problem. My 220D required hand pump priming to start if the car sat for more than a few minutes. I replaced all the braided line return hoses as well as the braided cigar hoses back at the fuel tank. The sure sign that I had a problem with failing hose causing the bleed back was that the hoses were wet with diesel (not dripping wet, but still wet with diesel). But, if fuel bleed back was a primary problem the car would be hard starting to one degree or another. At any rate, double check the hoses (and steel line) for signs of leaking diesel. With the car at a standstill when you run it above 2200 rpm is there any missing? I would think the lurching would be worse, in my opinion, when in high gear at low rpm when you give it a lot of pedal. But, if it only occurs above 2200 rpm under any load conditions, I guess this could possibly not rule out fuel problems nor slippage in the clutch mechanism (of whatever type).
So, check if the engine "misses" above 2200 under no load. Most likely, I would think, you have a fuel delivery problem. So, not only air in the system, but it could also be clogged filters, whether tank, primary or secondary filters. If they have some miles then put new ones in. Check fuel lines. Since this a new problem since you worked on fuel system, you need to rule it in or out first. If all is well, then check engine rpm during the lurching.