You have a FPR so pressure should be constant at 4 bar.
Check your pressure with a gauge.

It is possible your FPR or fuel return is inadequate/borked so that your actual pressure is going higher.

Everything you said in this post is wrong.

You are a little bit right but your conclusions are completely wrong.

It is true that pump's MAXIMUM flow differs between fuel pumps at a given pressure. "MAXIMUM" is the important word here. The pump always pumps at 100% of its flow at a current fuel rail pressure which is regulated by FPR installed in fuel rail. From there, the injectors dictate how much fuel is injected into cylinders and the rest of fuel is returned back to the fuel tank.

So long the fuel pump can flow enough for a given fuel rail pressure, it doesn't matter how much it actually can flow. If 100 l/h is needed and your pump does just that, 100 l/h or 1000 l/h, the system will not see any less or more fuel injected since the pressure will remain constant.

Now, you said that you tried numerous tunes and have the same problem. Are you injectos the same as the tune is using? The only reason I could think of why you could see much more at part throttle but almost perfect at idle completely incompatible tunes for your injectors' TVUB/KRKTE values. E.g. your injectors flow much more than KRKTE in tune indicates with large enough TVUB to mask this fact at idle... but rearing its ugly head in part throttle where KRKTE weighs much more in calculating fuel mass.

Well I am running brand new 630cc siemens deka IV injectors with a brand new set of primary o2s and 85mm maf. First we tought that my maf is on its way out so i tried with 2 other ones with no change. Then i replaced the o2 sensors to rule that out as well. Same results with both tony's base tune and berttos' file as well so it has to be hardware related. My FPR is regulating the system to 4.1-4.15 bar according to the gauge and I wonder if that would make much difference and give me about -10% partial values. Any ideas what else could it be, other than the return line being clogged? 

Meh I constantly fail not to spam the forum, but I forgot to share the logs after the O2 swap and driving around for 30 km.

https://docs.google.com/spreadsheet/ccc?key=0AhrG40GHpr-hdF9KTlhUd0VQZ2N1NmJ2d3JDMk5MSXc

I've only have the block 032 and 033 logs at the moment of a 30km drive. I won't be able to do any ME7Logger logging until tomorrow because I blew one of my IC hoses off.

Please get a single 3rd gear pull from 2500 to redline WOT.. thanks

From what i can tell though, your fueling looks fine post trim (req afr vs o2 voltages) but it is hard to say w/o wideband logs.

All i can think of is your old fueling had issues.

I'd just pull 10% out of KRKTE or MLHFM and see what happens.