1991 Audi 90 2.3E fuel leak

[IDUA90sport]

Hi all, New to the Audi World bought a 1991 Audi 90 2.3E 10V FWD about 5 months ago. From never having worked on a car I have learnt off the net. Since then I have changed a cv joint, changed broken blinkers and lights,changed oil, oil filter and transmission oil. Noticed my fuel efficiency took a dive then found fuel leaking from under the fuel injection/air filter area. Could not locate the source of the leak after taking the front bumper, lights and everything else off to try and see the leak. See photo: Red - arrows showing where fuel leaks from. Yellow - showing roughly where frame is that I cant see past to locate leak. Green - showing air filter box location, how do I get that out? Blue - showing all the stuff I am dreading taking appart to get to the air box and possible leake site below. The car is my daily driver so I had to stop searching and put it back together from about 2pm sunday so it would be driveable Monday morning. So far researching on the subject it seems that if the fuel injectors are leaking they could be expensive. I have a second 1991 Audi 90 2.3E for parts and am considering swapping the whole fuel injection set up over. Any advice or suggestions would be appreciated before I attempt this next weekend? Thanks.