1992 f150 with 302 and e4od

I went to put the truck into reverse today and after doing so it stalled, never done this before. However started right back up and drove home with it fine and nothing else out of the ordinary happened.

After returning home a pulled codes.
KOEO:
327-egr feedback signal low
634- mlp out of sensor (?)

KOER:
111-no codes present

I'm not 100% sure what code 634 is but I've been reading this forum and found that a symptom is occasional hard hard shifting which is what my truck has.

Any insight on these codes would be great and as far as it stalling randomly without setting a code any ideas?