197K miles, stock, regular maintenance to include fuel filter, runs great with the exception of the problem I am having and I can not find an answer to fix the problem for good.
I am on my 3rd stock fuel pump and every time I brought it to the dealership they just want to replace the fuel pump. It has happened just about the same way every time, soon after the warranty is done the sending unit will randomly malfunction and I mean random, it will just stop sending information but if the car is restarted it is fine. Next after a long drive, really hot day, or a hot start when going above 3-4K RPM my fuel rail pressure will drop below 20-25 PSI and my engine will start to die and lose power.
if I keep the drives short, under 20 minutes it is normally ok. So what can I do besides just replacing with another stock pump

 

Take it to another shop, I'd say. I'm sure the pump is faulting again, but maybe it's who's installing it...?

 

Houtex:
so far it has always been a ford dealership, so ether the dealerships are doing poor work or the parts they are giving me are poor quality. This time I am getting an aftermarket pump from summit racing that is almost identical to the stock version. Hopefully someone has an answer though for why all these stock pumps are failing

 

Well, the truth is if you've had three pumps happen to go out and all (except the first stock unit) were installed by this dealership, that would make me suspect of the dealership's installation procedure in some way, as it's extremely odd. You're either unlucky in this particular manner and just keep getting less-than-ideal parts from Ford, or the dealership service is messing up the install. I doubt the parts themselves were made any differently than the probable millions of units made over the years for all the Mustangs and other Fords that use the pumps.

But that's just me feeding the fire of a conspiracy I don't think is happening. Hopefully the Summit Racing pump solves the problem... but if it happens again... "well, there it is." - Ian Malcom, Jurassic Park.

Beyond that it may be a fuel pressure regulator (which isn't getting diagnosed, or very good reason it's not) or fuel pressure sensor (ditto). Possibly a wiring/connector issue. Or maybe the smart junction box or ECU. But since putting in a new pump fixes it for a year or so, sorta indicates it's not those. But I'm not the qualified Ford technician lookin' at it with scan tools and what not, so... I could be mistaken or something?

In any event, I wish good dang luck to ya and all!