3.0 misfire problem

[Dave king]

Hi all

on my 3.0 petrol i have a bad misfire on 1-5.

first i got crank sensor code, replaced and code gone.

mixed up the coils and still got 1-5 misfire.

changed plugs and ran great for 1 mile then back

to 1-5 misfire.

got a code now p1250 fuel pressure regulator.

changed the vac pipes but no luck.

would this cause a misfire....

All this has been since two days after i changed the coolant

sensor because it would not cold start.

 

Thank you very much.

dave king