Looking for some ideas.

'99 Dodge Ram 5.2L

About a month ago coming up to a stop sign, I had the truck stumble, start idling rough and then die.
Wouldn't restart. Popped the hood looked around for anything obvious, closed the hood, hit the key and it fired right up and was fine until last week.

g/f takes it to work, wouldn't start after it sat all day. She tried numerous times. Tried it with the throttle at different positions too.
Had it towed home. I hop in after it's dropped off the wrecker and it fired right up!

It didn't trip the check engine light on either incident.
I just scanned it for trouble codes.. nothin'
Tested fuel pressure... it's 49# before firing it up. 50# when it's running and with reving it. The needle does quiver rapidly about a pound, if that means anything.
Unfortunately I haven't been able to check for spark when it's not starting yet.

What next?