1988 Jeep Wagoneer stalling

I have a 88 jeep wagoneer and it stalls after starting most of the time.
when it stalls you can smell gas real strong and it doesnt die it just runs really rough at very low rpms
and backfires out the exhaust.
if I hold the accelerator to the floor it will clear out.
these things also occur every once in awhile as im driving hwy. Speed.
as I said before it acts and smells if its flooding.
the fuel pump, fuel filter, fuel pressure regulator, map sensor, plugs, wires, cap, rotor, have all been replaced.
my jeep has the 4.0L M.P.I.
could it be the idle speed stepper motor or an injector leaking? Any help would be appreciated