What caused the oil guage to jump, and the truck to act like it was out of gas?

What is your question?

My truck (2002 Ford Ranger) broke down while driving. The oil gauge was in the center, and then it begin to jump from high to low and made this strange puttering noise like it was running out of gas. It begin to slow down until it came to a complete stop. After that the truck won't crank but the lights and all still work. Oil was full, had near half a tank of gas. And no leaks were noticed.

What makes this problem better or worse?

It doesn't crank since it happened

How long has your 2002 Ford Ranger had this problem?

Was having problems cranking for a few years before this happened