Relatively long periods of wide open throttle will reduce engine vacuum which can shut down your petcock if it is the vacuum operated type. Any minor vacuum leak will show up first in these conditions. This condition is usually noticed first on the highway climbing a long incline in top gear.
Check all vacuum lines carefully by spraying with WD40 while engine is idiling (or on a 1994 it's probably a good time to just go ahead and change them anyway).

 

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My carburetor experience is huge but not Harley related. I think HOPTLAP may have nailed it.

 

Mine does not have the vacum operated petcock not on my year. The only thing that has vacum is the V.O.E.S. switch. could that switch cause this problem if going bad?
Thanks
Barry In MO.

 

No I think that would just cause ping or knock.
It does sound like it's starving for gas during periods of sustained high flow, might be worth having a look at that filter just in case.
Second place I'd look is at the carb float, might be catching on something and not moving down fully to let full flow to the float bowl.