99 Ford Ranger acts like its running out of gas

Is it more like a stumble, where the engine either cuts out entirely for a split second or loses power momentarily? If so there are a number of possible electrical AND fuel causes. FIRST, I'd try popping the distributor cap and inspect it -which I notice you didn't mention. A distributor cap androtor hve contacts that develop corrosion and are eroded over time by "normal" phyisical and electrical wear. Yours may show signs of eroded contacts, OR HAVE A BUILD UP OF CARBON INSIDE IT .If its contacts are badly eroded either dress them or replace it. If its just carbon, wipe or spray the inside of the cap with something to get the carbon off as CARBON CAN CAUSE A SPARK PATH TO BE ERRATIC (INSIDE the distributor or outside it) which will make a spark plug either not fire or fire at the wrong time ESPECIALLY LIKELY TO HAPPEN WHEN THERE IS MOISTURE PRESENT (like condensation on a cold engine) then i'd check as many ground wires as I could find that connect to anything in the engine compartment-not just t he battery/starter ground wires. Next I'd open as many connectors on and around the engine as possible to eliminate the possibility of having a poor electrical connection that could affect the ignition system. Be sure to check the connections at the starter solenoid, because the ignition feeds through that and a solenoid that is developing a poor connection could momentarily open the circuit before it fails completely. The distributor-mounted ignition module is notorious for failing and it will USUALLY go bad slowly, often causing hard HOT starts or ignition drop outs as it nears the end of its life. There is a very thin layer of grease that helps it maintain contact with the body casting of the distributor and if that contact area is getting dried out or in any way compromised by age or too much power washing or road salt the ignition circuit has a much greater chance of being adversely affected. As to fuel issues. Its possible you just got one tank of bad gas, or that there is water (from condensation) in your gas tank. A cold engine is less tolerant with running on marginal gas or gas cotaining just a little water. Than a warmed up engine. A new fuel filter doesn't stop water from coming through. If only a DROP of water comes through the fuel line, it will cause an engine miss, and any more water than that will cause a miss that's probably going to be noticed by nearly anyone. To help with (or eliminate that as a possibility) use a gas treatment-which you should be usuing from time to time anyway with a 1999 vehicle.

Is it more like a stumble, where the engine either cuts out entirely for a split second or loses power momentarily? If so there are a number of possible electrical AND fuel causes. FIRST, I'd try popping the distributor cap and inspect it -which I notice you didn't mention. A distributor cap androtor hve contacts that develop corrosion and are eroded over time by "normal" phyisical and electrical wear. Yours may show signs of eroded contacts, OR HAVE A BUILD UP OF CARBON INSIDE IT .If its contacts are badly eroded either dress them or replace it. If its just carbon, wipe or spray the inside of the cap with something to get the carbon off as CARBON CAN CAUSE A SPARK PATH TO BE ERRATIC (INSIDE the distributor or outside it) which will make a spark plug either not fire or fire at the wrong time ESPECIALLY LIKELY TO HAPPEN WHEN THERE IS MOISTURE PRESENT (like condensation on a cold engine) then i'd check as many ground wires as I could find that connect to anything in the engine compartment-not just t he battery/starter ground wires. Next I'd open as many connectors on and around the engine as possible to eliminate the possibility of having a poor electrical connection that could affect the ignition system. Be sure to check the connections at the starter solenoid, because the ignition feeds through that and a solenoid that is developing a poor connection could momentarily open the circuit before it fails completely. The distributor-mounted ignition module is notorious for failing and it will USUALLY go bad slowly, often causing hard HOT starts or ignition drop outs as it nears the end of its life. There is a very thin layer of grease that helps it maintain contact with the body casting of the distributor and if that contact area is getting dried out or in any way compromised by age or too much power washing or road salt the ignition circuit has a much greater chance of being adversely affected. As to fuel issues. Its possible you just got one tank of bad gas, or that there is water (from condensation) in your gas tank. A cold engine is less tolerant with running on marginal gas or gas cotaining just a little water. Than a warmed up engine. A new fuel filter doesn't stop water from coming through. If only a DROP of water comes through the fuel line, it will cause an engine miss, and any more water than that will cause a miss that's probably going to be noticed by nearly anyone. To help with (or eliminate that as a possibility) use a gas treatment-which you should be usuing from time to time anyway with a 1999 vehicle.