My 89 eagle has a

my 89 eagle has a v6 i have installed 4 used fuel pumps and when i getthe car going it runs fine till i get 20 miles down the road then it losses power till i drop it a few gears bring the rpm up high then it starts to gain till i slow it down im an old school mech i believe im going to need a brand new pump as the used ones arent any better than the one that failed. i think when the used pump gets hot it starts to restrict fuel i think a new pump will fix everthing i hope