"Real Time" by Lawrence Watt-Evans

First appeared in Asimov's.  Reprinted by Charles Ardai and Mike Ashley.

Protagonist stops time paradoxes from occurring.  He feels something in his telling him who/what will cause the disturbance and takes them out himself, vigilante style.  The question is "How reliable is our protagonist?"  It's a smooth transition from one style to another.

Another Watt-Evans story mash-up is "Windwagon Smith and the Martians", which mixes Ray Bradbury, Edgar Rice Burroughs, and the American tall tale.