I purchased a 1989 escort pony that wasn't starting due to fuel pump needing replacement and had done that. The car ran fine for awhile and then it started dying while cold I'd warm it up and the car would be fine and then it would take longer to warm and then eventually would die while warm and some forum, research, and advice lead me to replace the fuel filter and idle air control valve. That was 3 months ago and now I'm having the same problems and not sure where to go

 

When most folks replace a fuel pump assy, they don' t bother to check and clean the tank, which if it has foreign matter inside, the odds are pretty good the fuel problem is only temporarily solved.
If that was done, and filter changed as mentioned, you might take a look at the ECT,(Engine Coolant Temp Sensor). If it is registering as the engine is warm when it is not, the engine will run lean and possibly stall.

 

If the engine dies and won't re-start, check for loss of fuel pressure or spark. Many aftermarket fuel pumps are junk and fail .Diagnose first before changing anything as misdiagnosing can get expensive.