Vacuum leaks are not easy to detect (in general) as they can be the at throttle body, intake manifold, a sensor, a hose leading off somewhere, etc. etc.. Really depends on what's leaking and where. Some people might use a spray (gotta be careful, most are flammable, oils can catch fire later if they soak, etc.) on a cold engine (start engine after fully cooling down) and spray around the intake ports, throttle body where it attaches, vacuum lines while moving them with free hand, etc. and listen for the engine to surge or possibly stall. That can help pinpoint *some* leaks or let you know something needs attention.
Vacuum hoses for example, especially once they get some age, might "feel" OK where you touch it, but could be hardened at one end on a metal/plastic nipple and brittle, to the point it'll slip right off or effectively fail to seal. Might go a year before the leak is bad enough the engine throws fits. I've seen vacuum hoses soft and mushy on a bend (basically rotten) but seemingly "OK" the rest of the way. Heat, oil, etc. will shorten their life span as well. Plastic lines can actually split on a bend, but you'll never know it until you move it. And if the engine is rocking slightly under harder acceleration, that might be enough to expose a leak or make it bad enough to detect, then once the engine rocks back to rest, it seals. Heater hoses can do a similar thing where they develop a pin hole that only leaks at certain pressures, but self-seals the rest of the time, making it tough to find the coolant leak. Being you are in the desert, there are going to be inherent challenges to keeping a car on the road. From maybe having to run a slightly thicker oil, to paint fade, dry rotting hoses, etc.
Personally, I've gotten into the habit after buying a used car to including replacing all the vacuum lines (if possible, some cars have odd jump sizes; think of a tobacco pipe where one end is 1" and makes a 90 degree bend to the other end which is 1/4"; have to get creative if it's no longer stocked). I'll go to the local auto parts store, pop the hood, verify all the sizes are roughly the same or not, then go in and buy 5 to 10' of vacuum hose (if most sizes are about the same, snag one from the car and take it in so they can find a similar size). It costs about $10-20 total and is sold by the foot. Do ONE hose at a time. Some cars might have 4 or 5 nipples right next to each other, and reversing just one hose might ruin your day. If all/most of the nipple ends are plastic, you have to be EXTREMELY careful with regards to removing the hose off of it. Twisting or pulling might break a brittle plastic nipple end, and now you need a new sensor which might not be easy to find. My advice is lightly score the hose end, length-wise until you see plastic. It'll come off easiest using that method. Attaching new dry hoses poses a similar challenge. A drop of something that won't hurt the rubber but evaporates can help slip on easier.
Anyhow, I'll go through, one vacuum hose at a time. Vacuum lines to Emissions stuff is usually finicky with popping codes, so having fresh hoses there is important. Usually what I've noticed after doing all the lines (regardless of any issues beforehand), is the cars in question seem to idle more reliably, and run smoother. Vacuum leaks can cause odd things like running lean, erratic idle, codes pointing at sensors they connect to, etc.
For $10-20 and 30-60 min, is very cheap piece of mind. Worse case, you still need to replace a pricey MAF, but lines should be good for another 14 years and it possibly eliminates other minor drivability issues or acts as a preventative.
If you don't want to guess, have Ford do a diagnostic ONLY. Say "I need you to verify why the code appeared. I'm not sure how I want to handle the actual repair yet". If they say "MAF", that's something you can replace yourself. If they say "vacuum leak", ask them where it is and get a quote. Most likely you can do it for next to nothing. If they say "intake manifold", it's something that's DIY if you want to save and are inclined to replace the gasket. Then again, you might have an electrical issue that they are better suited to tackling.
