What is "Bad" MPG for a '94 5.7L ?

[Supercharged111]

The wax pellet?

 

[L31MaxExpress]

I was under the impression it was to mix warm air with the fuel?

Which it does. Keeping the inlet air temp relatively constant helps keep the fuel delivery and therefore BLM value stable. With an open element the BLM values will be all over the place.