I'll spit out the common stuff.
First of all... you have the SOHC, not the OHV version. 2001 was the crossover year to SOHC.
Is the coil pack an aftermarket, or a Ford Motorcraft unit? How about wires and plugs? EEC ignitions in Ford products do not play well with aftermarket stuff. It might seem like a good idea to do Bosch plugs and spiral core wires and an Auto Zone coil, but it isn't. Ford parts from the counter are usually just a few dollars more than the parts store, and they are a must. Performance upgrade? Not really, but they'll work right every time. You can get plugs anywere as long as they are irridium Motorcraft in the right application. Some parts stores carry Motorcraft stuff so you might get lucky. Amazon is your friend here unless you have a convenient dealership parts counter. Just order your ignition parts by Motorcraft part number. This is absolutely one application where stock ignition parts are the way to go.
Intake stuff. These 4.0L are very particular about their airflow. The throttle body is a big offender. They might look OK from the outside with just a little carbon tracking, but often times the backside of the throttle is nasty. Pull it off, take the TPS off, and soak it for 20 minutes in parts cleaner. Scrub the crap out of it, literally. While you're at it, pull the EGR and IAC to check for crusties. Suck on the EGR vacuum hose and watch for proper operation of the valve. If it's sticky or doesn't move, replace it. You have to suck hard, but you should be able to get it to move. The gaskets are paper for the TB and IAC, and that carbon printed material for the EGR. All three are easily re-used if you're careful.
Dirty MAF will cause this and it's super easy to fix. Take the MAF out of the housing being a little careful as it is an exposed super-fine filament. Blast it off with a few squirts of MAF cleaner and re-install. Other solvents work as well. I have used brake cleaner with success, but some say that DeOxit or carb cleaner leaves residue that can cause problems. Basically what happens is, the MAF filament gets coated and insulates itself. The way the MAF works is by heating that filament. Less air flowing over it means it is hotter and has more resistance. When it gets coated and insulated, it reads as less air than is actually flowing past it. The ECM injects less fuel until you get to a point that the O2 and MAF reach their opposite limits of +/- 20% and the ECM says "wait... WTF."
Fuel pump relay is a known failure point. Often they present as no-start when hot, but they can cause the issue you're describing. They get hot during operation and the coil starts drawing extra amperage. That weak activator coil, plus years of the contacts getting corroded can make them fail. Very hard to test since it only happens once in a while. Mine I finally was able to diagnose because it wasn't making fuel pressure but I had a good crank position signal. I swapped out the fuel pump relay with the EEC relay and suddenly got fuel pressure, but no crank signal. Bingo. New $11 relay fixed the problem.
Your temperature gauge is 100% normal. Every Ranger/Exploder/B-truck reads the same way. It's a semi-dummy gauge. The temp sensor reads full range, so if you put it in a pot of water and heat it up, it will show a linear resistance change. The gauge reads three basic resistance ranges; cold, normal, and too hot. The assumption is that consumers like to see things cool, so the "normal" range shows on the low side of middle. Best way to check is an IR thermometer on the t-stat neck to verify actual temps.
Fuel pump is also a known failure point, but in every situation I've seen, they just quit. I suppose it's possible that you are in the failure period when it's slowing down and not providing adequate pressure, but the best way to test that is to just drive it. If it craps out, you know. Somewhere over around the brake booster is a fuel pump test connector. I forget which one it is. If you have a multi-meter that can do 20A, hook it between the battery positive and that test wire. If you get low/no amps and no pump, the pump is toast. If you blow the fuse in the multimeter you have a short - either in the wiring or the pump. If you get X amps and proper fuel pump operation, your pump is fine. That test is pretty easy to google.
It's also completely possible it was a hiccup. The OBD won't trip a code until it has reached a threshold of a certain value depending on the fault. For instance, an O2 heater circuit will trip a CEL right away because it is either in-spec or not, but a fuel pressure code might wait until it passes the threshold 3 times. Other things like crank position sensor might not even set a pending code until 100 blips since that is a high-resolution sensor that gets hundreds of signals per second.
