reoccurring starting problem

[Wrencher]

I'm looking to possibly purchase my neighbor's '99 Ranger, 3.0 with automatic. Last week, I was going through it, trying to find the cause for the rough idle by pulling plug wires.After shutting it off, it would not fire. Later that evening, my neighbor started it up repeatedly without issue.
Yesterday I again went to look at the truck. After my neighbor started it up, I made the comment that I bet it wouldn't start again. Guess what, it didn't start. Today I get a call that it's running.
So what am I looking for? Is there something tripping and resetting? Shut-off switch has been removed and check engine light isn't on.
Thanks for any advice.

 

[john112deere]

When you say "won't start" do you mean it won't turn over at all? Or that it will turn over but not actually start?

Did you check for spark and/or fuel when it's not starting?

 

[Wrencher]

It turns over but won't fire, I got a very weak spark at the distributor plug wire connection that was strong when the vehicle was running. Basically ruled out fuel and didn't check.