My 97 3.3 dies while driving. Speeds probaly at 25 to 40 mph. It also gets harder to start after it is warm, turning over longer than usual. Recently changed, plugs, fuel pump, fuel filter - coil, wires and idle motor changed within last 3 years and injectors cleaned within year.

 

tough to diag over the net, I'd guess crank/cam sensor. They usually do not set a fault when they go out.