Ford: Starting problem, fuel pressure regulator, haynes manual

Question
QUESTION: (I know its not a mustang but thought maybe you could help me) I have a 98 Ford ranger VIN# 1FTYR14X7WPB32758 with 4.0L OHV got bad gas truck had no power and wouldnt start right would lope and miss for bout 20 to 30 sec then idle up. Replaced the fuel pump assembly and got plenty of power now but still doesnt start right when the truck sets over night. Replaced fuel filter plugs wires IAC coolant temp sensor air charge temp sensor coil egr valve no check engine light truck runs fine after u get it started was going to replace fuel pressure regulator but haynes manual says in my year its in tank already changed whole assembly looked at my old one and didnt see a regulator and I took thing off my fuel rail that looked like regulator called ford with part number it is a pressure damper so where is my regulator and could damper be causing my problem hooked fuel gauge to rail pressure was slowly backing off Im stumed its been a yr  please help me Thanks.

ANSWER: If it ia loosing pressure it could only be a couple of things.. it could be a bad check valve in the fuel pump... (I understand it is a new one but new does not always mean good... ) or the injectors... you could have a leaky injector... how many lines were comming out of the pump?? if only one than it has an internal regulator if there is two than the regulator is on the fuel rail... let me know and we can go from there... (Sorry for the delayed responce...)

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QUESTION: It had 2 fuel lines but the only thing on the fuel rail is that fuel damper took the truck to ford this past mon they hooked it up to a machine and said there was no codes and that the truck started fine when they drove it said once it warmed up it was loading up a lil bit but that was it and to try replacing mass airflow. They also said fuel pressure was within spec.

Answer
Did you replace the IAC with an aftermarket or a Motorcraft... I have installed a lot of IACs and will only install Motorcraft ones... (I have had to replace a lot of the aftermarket ones I have installed with Motorcraft ones...) unfortunatly without lookinf at the truck there is not a lot more that I can do... Sorry for not being much more help...