1990 Pathfinder not starting

[Carskick]

It doesn't do this at home in Florida, just on trips. Usually starts happening on the 2nd day of the trip, the car will crank, but not catch. It can take many tries to get it going. Sometimes it floods. It often sputters or idles high once started. I've installed a new fuel and air filter, and the problem continues. Please help, it's very fusterating.

BTW, I took it to the dealer in Arizona on my last trip when it was doing it, and they did a diagnostic, found nothing, and of course could not get the car to crank and not start. Figures.

My unkle had a similar problem in his 90 Pathfinder, and it turned out to be the O2 sensor. But it costs about $200 to replace! And we're not even sure that's the problem. ARG!