Cutting out on Highway!-Where to start looking

[Michael A.Carr]

Subject is an '87 5kTQ..... Driving along no strain, not pushing it... 
(only .5-.8 bar) avg speed 70mph, and nothing I could detect with the 
stereo off, when poof no sounds just a stuttering little dip in the nose 
and I could tell the engine was off. It retsarted without hesitation by 
turning key in ignition switch, while I was still cruising with my foot 
on the clutch peddle.... happened 4 or 5 times, but made it home fine 
and there's no problem starting, though the fuel pump has been 
humming... That it?