1991 Nissan hardbody won't start after stall?

I'm the second owner of a 1991 Nissan hardbody in excellent condition with just over 60,000 mi. It was well taken care of before I got it about a year ago, with no rust and no cosmetic issues other than a couple of scratches and faded paint. It was a fleet vehicle and well maintained from what I can tell but don't have the records. My issue is that it when it is stalled while driving, 50% of the time it won't start up until it's set for probably 20 minutes or more. It will crank and sound like it wants to start but it won't catch. The fuel pump seems to be strong, I've swapped out plugs and done some basic research but I can't come up with anything.

This is stranded me a couple of times and I'd very much like to fix it. Does anyone have any ideas?

Thanks in advance