Resurrecting the '97--Fuel system trouble. Please HELP

Hey folks,

Recently got rid of an '03 SE7 so I could get back into a 97 SE7 that has been sitting idle in the midwestern elements for more than a year now.
The gentleman who I sold the 03 to installed a new fuel pump in the 97 as part of our deal for the newer car.
I thought that was going to fix the problem but we're not there yet.
Any help I can get here would be much appreciated.
Here's what he has seen/done to the thing so far:

Have a problem with a 1997 disco advanced evap 125k miles
it quit running about a year and a half ago. no gas pump noise in back.
replaced pump with an airtex 3270,turn key pump works but….
tried to start had to cycle the key a few times and vent the schrader valve fired up but only idled when accelerating would cut out.
tried with MAS disconnected figuring it was bad no difference thought Mass airflow sensor bad
had put a K&N in not too long before it quit,got new one no difference.
can kind of pump it to get higher rpms did get it to run at 2500-3000 smooth but put in drive no power and little backfires noted
pressure at pump gone after key off ok with key on pos 2 but not going out to the fender
took output line off hooked up a gasoline to a gas can and flowed well like a water hose.
figured filter bad. wrestled it out was some restriction but not plugged replaced it and still no difference
did hear a trickle of fuel? returning to tank when pump running ,fuel pressure regulator?(vacuum line checked and tight to press reg.)
I Am at wits end any ideas ?


----Thanks in advance for any guidance