Old blob-based horror movie with a kid on a bus?

I saw this on a little tiny tv way way back, probably 1990 or 1991.  I was a kid, and this was the only scene I remember.  It was in color.  A kid walking onto a bus or into a hallway, something like that (he is backlit) and he sees a dude laying down with his mouth open at the back of the bus or at the end of the hallway. A fly lands on the dude’s face (he may have had a mustache?), and goes into his mouth? But then some kind of blobby, goopy stuff starts to crawl out of the dude’s mouth and the kid runs off.

This has been bothering me for decades!  Help!

2 thoughts on “Old blob-based horror movie with a kid on a bus?

    1. I thought so, too. I bought the movie specifically hoping it was the right one, but it is not The Stuff. The fly going into the dude’s mouth is the most vivid memory of the movie I have, and that isn’t in the Stuff anywhere.

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