Have you tried bypassing the ISV? You can unplug it from the j-boot and cap off the vacuum line/hole in the j-boot with your fingers while someone else starts the car. You can also use some small corks to plug the hole in the j-boot/vacuum line going to the ISV. Just make sure they're big enough to not get sucked in. If you don't want to try those, you can jump ports B&C on the test port to the right of the brake booster (looking at the front of the car) or just disconnect the ISV, but that's almost impossible with the intake on. There's more info on Clark's Garage on bypassing/testing the ISV.
Any moisture/cracked solder joints in your DME? Just because the AFM is getting power doesn't always mean the DME is working correctly. Have you tried another DME? Are your speed/reference sensors working properly? TPS working/adjusted correctly? Have you tried pressurizing your intake and listening for leaks? I don't have the video handy, but if you search on YouTube Van posted a video about it how to do it.
Edit: ISV info:
http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/481223-idle-control-valve-testing-procedure.html
http://forums.pelicanparts.com/porsche-944-turbo-turbo-s/330312-idle-valve.html
Speed/reference sensor testing:
http://www.clarks-garage.com/shop-manual/ign-02.htm
TPS checking/adjustment:
http://www.clarks-garage.com/shop-manual/fuel-06.htm
DME cracked solder joints info:
http://forums.pelicanparts.com/porsche-911-technical-forum/652375-dme-bad-solder-joint-repair.html
Intake pressurizing to check for vacuum leaks:
http://www.youtube.com/watch?v=AL3jbcrqY8g
The car in the video is a turbo, but it'll work on any version of the 944.