Consider doing a smoke test when cold, and another when hot.
see
http://www.automotiveforums.com/vbul....php?t=1040810
Maybe it's too cold in Alaska to throw a DTC!
A smoke test is around $80
A smoke machine is $1200
see
http://www.youtube.com/watch?v=FfiQ7qWiG-M
Caution - It already sounds like you pin-pointed the problem with starting fluid, but using starting fluid is dangerous.