I agree with Wade. Also, old Porsches used L-Tronic EFI as well. If you can find an old school european auto repair shop it might be a good place to start if you are looking for a shop. If your car is just running rich, there are write ups on how to adjust your AFM. I would be interested to know if you have tried opening it and looking at the board. Even on the AFM you say has a dead spot, it may just be debris or something on the surface that the arm swipes. Check out the link below from Atlantic Z. Don't be afraid to dive in to your EFI. They really are not that complicated and very rarely can you break it. http://atlanticz.ca/zclub/techtips/afm/index.html Another area to check is your coolant sensors. On a 280z there are 2, a Thermotime sensor and temp sensor. Someone in the past may have gotten the plugs mixed up. Check a service manual and confirm they are hooked up correctly. Also, use an ohm meter to check the resistance of each sensor. If one or both are bad that could be causing your car to run rich too. Keep us posted on your findings.