There are several reasons why this may happen.
1. check your timing
2. fuel flow / fuel preasure. carb is not operating properly.
3. depending upon the load your engine may no longer be strong enough to pull it.
W/ 360 engine,my 1988 GWweighed 4480 lbs.
In a 1987 it's under the steering column, to the left. Hope it's the same for the 1988.
inside the alternator
twenty gallons
the v8 is 14.0 qts
Driver side
20 gal
Ford Motorcraft 2 barrel
Dana 44 front and rear
in the middle towards the back. my 88 has a yellow dipstick.
With an AMC 360 V8, it is 5000 pounds
15.5 quarts plus 1.5 quarts in overflow tank