By "after shifts it feels sloppy again" I mean the following:
When it shifts it really kicks into the new gear, especially at high RPM shifts. But shortly after the shift the firm feel is gone. When I really step on the gas the engine revs up and the car gets pulled forward quite hard, but then the acceleration goes away steadily even if the engine is reved higher.
I do have a shift kit for HD-use and a 13 vane pump installed, can that be a problem? I read somewhere that 13 vane pumps don't produce the volume a 10 vane pump produces, but can create higher and more constant pressures, so I threw it in. So maybe the pressure is high enough for the shift, but then the volume of oil isn't enough to fill the clutch applicating pistons... But I shouldn't think that would be a problem... Maybe I should pull out the shift kit, which does feature bigger holes in some of the oil feeds, but all that would cause slip in the clutches...

@ Typhoon: I had this problem with my old TC, and I thought it might be a TC-fault, so I bought a brand new one and it's exactly the same. I.e. it's not the TC, I don't think I would get a TC brand new that just happens to have the same fault my old one had. Anyway, how can a TC break? The clutch can get worn, but all other parts are surely not prone to deterioration, except for the stator sprag and bearings maybe, but they last quite a time...

This is where my problem is: I built the trans myself and it works, but not to my full satisfaction. And I can't find the fault. I'm really stumped by this one, especially because I don't seem to be breaking anything, everythings new, just the performance is lacking...