Its a fuel injected straight six. Trying to help a friend out, who is on a buget.

It seems that after the vehicle has been warmed up, or driven for a while, that it immediately stalls out. He has tried popping the clutch while moving down the freeway to restart but it won't, he has to physically turn the key again for it to start. Tach drops to zero also, after it stalls.

Does this sound like the ignition switch, coil, ignition module, etc? How would one diagnose what exactly it could be? Any ideas based on the above symptoms? Thanks for the help!