1991 Toyota 4Runner advise.

1991 Toyota 4Runner Four Wheel Drive Automatic

hi there.
ive recently bought a hilux surf off of my mate. We used to drive together so I know it was working fine for long.
i drove it for a few days with no problem but on my first day using it for work it drastically lost power on the way home, very jerky.
my mate took it in and replaced some filters and the jerking stopped. As the days went on it just lost power a lot, especially on the uphill and on the flats, downhill seemed ok.
i took it in for diagnostics and it came back saying check fuel pump and wiring loom.
these people say it will probably exceed £600.
loads of my friends advise me that im getting ripped off. Does this sound right or should I take it somewhere else?
please help me out here.
kind regards, paul.