ReadMyACARS - Assuming the Inmarsat doppler values are accurate, I ran the math which gave me the track and speed.
Inmarsat Values
[[2014/3/7 19:40:00, -109],
[2014/3/7 20:39:59, -140],
[2014/3/7 21:40:00, -169],
[2014/3/7 22:40:00, -202],
[2014/3/8 00:11:00, -250]]
Assuming a straight track heading 182, mach 0.39 @ 12000, the predicted doppler values are very close: [-102.21237107180059, -140.52053354680538, -174.36227202415466, -204.76829959079623, -247.19930766150355].
No other combination of speed and track comes close.
But with such a slow speed, the plane could not have headed off towards the west for long. It would have pretty much very quickly had to start heading south at around 0.81. The other Inmarsat doppler values support this. Then slowed down and dropped altitude at around 19:00 GMT.
Full details and kmz file see zs6tw.wordpress.com