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That is a very cool rig . Your Trip sounds like lots of fun. I like driving around the US.

It does not mater what you call it. The pressure gauge needs to go in the port nearest the engine. If you have the right scanner you can test the EGR. That EGR Reference was for a different post. It would cause your symptoms also.

The link I finally found for P141A is an EGR code see if this helps. https://www.engine-codes.com/p141a_ford.html

if there is a blockage it will be the first converter. The trouble code P141A has turned out to be an EGR code. If the EGR valve is not fully closing for the idle it would definitely affect the idle and lower the power. https://www.engine-codes.com/p141a_ford.html

if the catalyst is coated the Cataclean will help, but if the grid is plugged with carbon or dirt it won't Not sure where the cat is on the gen 1 . on the gen2 it is part of the head pipe so there is no chance of clearing that one.

This is a good section of an online source AA1 Car How Much Exhaust Backpressure is Too Much? Backpressure readings at idle on most engines should generally be less than 1.5 psi (10 kPa). This will vary somewhat from one vehicle to another depending on the design of the exhaust system, the size of the pipes, how restrictive the converter, muffler and/or resonator is, and whether it is single or dual exhausts. We've seen some idle readings as high as 2.75 psi on a few vehicles, but for most 1.5 psi or less at idle is normal. A partially restricted converter, muffler or pipe may flow enough exhaust at idle not to cause a problem, but chokes breathing at higher engine speeds. So to test this possibility, you need to rev and hold the engine at 2000 rpm. A "good" reading on most engines at 2000 rpm should be 3 psi (20 to 21 kPa) or less. Again, there may be some vehicles that will read a little higher that don't have a problem, but the reading should not be significantly higher. Pay close attention to what the backpressure reading does while you are holding it at 2000 rpm. If it remains steady, chances are there is no restriction. But if the reading gradually increases, it means backpressure is building up and there may be a blockage. If you want to rev the engine higher, say to 4000 rpm and hold it, the backpressure numbers will shoot up. Most stock exhaust systems will show backpressure readings from 4 to 8 psi (27 to 55 kPa), or even higher. As before, if the backpressure reading is unusually high or it continues to climb at a steady rpm, it usually means there is an abnormal restriction causing an unhealthy increase in backpressure.

I will check and see if i can find a link.

The scanner selection is very large , If your tech has the right one there are lots of test they can do. I have not had the opportunity to scan a Gen 1 TC so I do not know what you can interact with. You should be able to see the cyl Misfire info for all the cylinders. I am pretty sure that the injector pulse information should be available also . I am currently using A Launch scan tool It has good coverage. The Chinese documentation is, how do you say "Greek to Me" Did you say you pulled the coil power one at a time? If so what was the RPM Drop for the Cylinders? Do you remember the Compression readings? Comparing the two TCs how much less power does the 2012 have would you guess ? If the Compression is the same for all the Cylinders, The Injector swap for fifty bucks would make the Tune up complete . If there is no difference then when you change the O2 sensors it will be easy to put a pressure gauge into the pre cat hole and see how much back pressure the converter is causing. I have had several converters that are not bad, but are plugged up with carbon and dirt , They Rob power and fuel economy, and restrict the full load performance. Keep the up dates coming.

You need to find a tec with a good scanner . You can Check the tps sensor by taking the boot off the throttle housing and have some one step on the gas key on engine off if the tps is working. the throttle plate will move. the o2 sensors are on the head pipe on either side of the converter. If you have an injector Issue swaping the 2-3 injectors for the 1-4 injectors will move the missfire. A good scanner will give you a lot of running info. it will also allow you to drop cyl's 1 at a time to check the rpm drop. One more thing to consider is the converter could be papartially blocked with 220000 on the clock.

How does the tc run off idle when driving or excelleraing? How do you know the o2 sensors are bad? When you swapped the plugs were they replaced? When the coils and plugs were changed was the tc scanned again?

Here is a link for the O2sensor code. https://www.obd-codes.com/p0141. This is an o2 sensor code. The p141 is a transmission related code.

You need to look at the third brake light socket sounds like a problem with that socket and that could short out causing the fuse and the switch to fail.

Thanks Don a good catch, as english is not my strongest skill. The computers in the tc all require some power to matain memory. There is always some draw. You need an accurate ammeter with a low enough scale to see what the actual draw is and is it enough to kill the battery.

You need an low range ammeter to put in series with the battery and then start pulling fuses till the draw goes away. After the fuses then you start pulling relays. That is a good way to start .

How far from straight do you have to turn to get the noise? Have you had some one walk beside the car when you go forward and turn at slow speed? The fact that it is a clicking noise says cv joint. What kind of service are the Tc's in?