yep, i saw your post there ! its seems a good price for one thats already built and tested. i remember simon was quite happy with it at the time.
yep, the whole benefit in the MS is that it eliminates the AFM. What does it use? like all good modern system it uses a MAP sensor. Manifold Abolsute Pressure. It measures in the ECU with a pressure sensor how much air is in the plenum. You simply intercept the hose already there or install a bung in a custom intake system to provide a vaccum hose straight to the MS unit. Completely unobtrusive. The l-jet AFM was built for a car released in 1981, they didn't have that technology available for the manufacturing conditions of that time. The AFM is simply a mechanical means of measuring the air simply by tying a variable resistor to the movement of the flap, hardly ideal.
whats worse is, at one point or another the AFM measurements cut out at high rpm and the fuel curve is left to the hard wired program in the l-jet ecu. That means all sorts of problems for cars that draw more air than stock at high rpm. (it's run lean) A fully programmable system like the MS or similar allows the exact (or close to depending on programming) fuel requirements of your engine to be met at any rpm regime you have mapped it for.
so, i highly recommend it given your AFM woes, i'm sure you'll never look back.