My 1987 f250 efi straight 6 4 spd starts and then dies 90,000mi

Stalling out
https://www.google.com/search?q=1987+Ford+E250+stalls+out

Bad gas mileage
https://www.google.com/search?q=1987+ford+e250+bad+gas+mileage

Expected gas mileage

Gas Mileage of 1987 Ford E250 Econoline

Fuel Economy (.gov) https://www.fueleconomy.gov > feg > bymodel > 198...
1987 Ford E250 Econoline ; 6 cyl, 4.9 L, Automatic 3-spd · 14 · 13 · 15 · 7.1 gals/ 100 miles ; 8 cyl, 5.0 L, Automatic 4-spd · 13 · 11 · 16 · 7.7 gals/ 100 miles ; 8 cyl, ...

Can you get the diagnostic codes from the vehicle?

engine stalls.
can be 50 reasons
but are this.
needs a 60k mile tune up bad.
1: EFI system has 12vdc power loss. (see dash dim?)_
2: engine misfires. horribly and idle controls failed, (all will like that)
3: engine floods, same.
4: engine fueling drops so low and lean the engine stalls.
5: bad engine, cam time or sparking way off or 45 other engine prob.
there is a test for each one, need a list?
and last, 6: the ISC is stuck close, or EGR stuck open

did you pull the DTC scan codes, the CEL blink test?
from the ECU?
is the CEL glowing (lamp in dash) running?
omg, this is not a carb engine is it, many 87 were.
1987 is a cusp year, in USA for end off all carbs. (EPA rules)

check the fuel pump

A.T., 4x4, AOD (5.0L)
EAC}G}}400" type="radio" name="userInterchange" />A.T., 4x2, AOD (5.0L), 11-1/4" ext hsg
EA}}}400" type="radio" name="userInterchange" />M.T., 4 spd (Warner T-18), 4x4
M.T., 5 spd, Mazda/Toyo Kogyo, 4x4
M.T., 5 spd, ZF, 4x4, 8-460 (7.5L)
M.T., 5 spd, ZF, 4x4, 8-445 (7.3L, diesel)
EAA}N}}400" type="radio" name="userInterchange" />A.T., 4x2, AOD (5.0L), 10-1/4" ext hsg
M.T., 4 spd (Warner T-18), 4x2, 12" ext, cable drive speedo
M.T., 4 spd (Warner T-18), 4x2, 12" ext, elec speedo
M.T., 4 spd (Warner T-18), 4x2, 4" ext, cable drive speedo
M.T., 4 spd (Warner T-18), 4x2, 4" ext, elec speedo
F>}A}}400" type="radio" name="userInterchange" />A.T., 4x4, C6, 8-460 (7.5L), (elec speedo), (tag F2TP-YA)
M.T., 5 spd, ZF, 4x2, 6-300 (4.9L), cable drive speedo
M.T., 5 spd, ZF, 4x2, 8-351 (5.8L), cable drive speedo
M.T., 5 spd, ZF, 4x2, 6-300 (4.9L), elec speedo
M.T., 5 spd, ZF, 4x2, 8-351 (5.8L), elec speedo
M.T., 5 spd, ZF, 4x2, 8-460 (7.5L), cable drive speedo
M.T., 5 spd, ZF, 4x2, 8-460 (7.5L), elec speedo
M.T., 5 spd, ZF, 4x2, 8-445 (7.3L, diesel), cable drive speedo
M.T., 5 spd, ZF, 4x2, 8-445 (7.3L, diesel), elec speedo
M.T., 5 spd, ZF, 4x4, 6-300 (4.9L), ID E9TA-TA & TB
M.T., 5 spd, ZF, 4x4, 8-351 (5.8L), ID E9TA-TA & TB
M.T., 5 spd, ZF, 4x4, 6-300 (4.9L), ID F4TA-BA & BB
M.T., 5 spd, ZF, 4x4, 8-351 (5.8L), ID F4TA-BA & BB
>C}}}400" type="radio" name="userInterchange" />M.T., 5 spd, Mazda/Toyo Kogyo, 4x2, elec speedo
>D}A}}400" type="radio" name="userInterchange" />M.T., 5 spd, Mazda/Toyo Kogyo, 4x2, cable drive speedo, 2.73 ratio
>D}A}}400" type="radio" name="userInterchange" />M.T., 5 spd, Mazda/Toyo Kogyo, 4x2, cable drive speedo, 3.08 ratio
>D}B}}400" type="radio" name="userInterchange" />M.T., 5 spd, Mazda/Toyo Kogyo, 4x2, cable drive speedo, 3.55 ratio
>D}B}}400" type="radio" name="userInterchange" />M.T., 5 spd, Mazda/Toyo Kogyo, 4x2, cable drive speedo, 4.10 ratio
A>}}}400" type="radio" name="userInterchange" />A.T., 4x2, E4OD, 6-300 (4.9L), (elec speedo), ID F2TP-BA
A>}}}400" type="radio" name="userInterchange" />A.T., 4x2, E4OD, 6-300 (4.9L), (elec speedo), ID F2UP-DA & DC
A>}}}400" type="radio" name="userInterchange" />A.T., 4x2, E4OD, 8-302 (5.0L), (elec speedo), (ID F2TP-DA)
A>}}}400" type="radio" name="userInterchange" />A.T., 4x2, E4OD, 8-351 (5.8L), (elec speedo), ID F2TP-FA
A>}}}400" type="radio" name="userInterchange" />A.T., 4x2, E4OD, 8-351 (5.8L), (elec speedo), ID F2UP-EA, EB & EC
?}}}400" type="radio" name="userInterchange" />A.T., 4x4, E4OD, 8-351 (5.8L), (elec speedo), (ID F2TP-HA)
}}}400" type="radio" name="userInterchange" />A.T., 4x2, C6, 8-460 (7.5L), (elec speedo), ID F2FP-CA & DA
A.T., 4x4, E4OD, 8-460 (7.5L)
E}}}400" type="radio" name="userInterchange" />A.T., 4x2, E4OD, 8-445 (7.3L, diesel)
A.T., 4x2, C6, 6-300 (4.9L), w/o ID F2FP-BA; w/o ID F2UP-CA
A.T., 4x2, C6, 8-351 (5.8L), w/o ID F2UP-CA
A.T., 4x2, C6, 6-300 (4.9L), w/o ID F2FP-BA; ID F2UP-CA
A.T., 4x2, C6, 8-351 (5.8L), ID F2UP-CA
A.T., 4x2, C6, 6-300 (4.9L), ID F2FP-BA
A.T., 4x4, E4OD, 8-445 (7.3L, diesel)
A.T., 4x2, E4OD, 8-460 (7.5L)
A.T., 4x2, C6, 8-445 (7.3L diesel)
EF}D}}400" type="radio" name="userInterchange" />A.T., 4x4, C6, 8-351 (5.8L)
Good luck

What a great truck I've had two, one I drove around in mexico for 6 months. You need to change the fuel filter. It is located under the truck on the fuel line coming from tank about even with the seat. You need a wrench set. Make sure you have the arrow on the new filter going the proper way, toward the motor. Good luck, thats a tough truck

The fuel pump is in the fuel tank,it needs to come down to replace the pump.Probably a 4.3l v6.

Got fuel pressure? Fuel Pump 20 years old?

1-3-7-2-6-5-4-8.

float stuck in carb,bad fuel pump or filter