Hi Matt

I want to remind you, I do not know anything about the front wheel drive cars. I have never looked under a hood of one any farther than to give it a cringe 😬!
I think you are on the right track now by placing 👀 peeping windows in strategic locations.
One noid light will tip you off to a failing injector firing system.
All injectors are fired in pairs or strings by grounding “almost” continuously in order to get enough gas into the intake and to the cylinders fast enough.
Those Pistons are flying, even at idle, with parts of a second to work.
Pulse widths times cannot be seen and is irrelevant in this case of a failing to start issue. No oscilloscopes needed.

It appears that the clues are pointing to this is an electrical thing. You have scared it by being very close, Since you moved those couple of items and the symptoms changed!
This, even though those items are not affected by engine heat per say but could be from operational use or components heating some.
I like the idea of cracked solder joint but connector clips, are even better and some under the hood.
Have you ever applied a thin film of corrosion prevention? I like a salve or LPS One or Two for a light dusting and check for deformities
The AMM connector on the 240s are notorious for releasing after years of earlier guesses and hunting.
Not that a AMM causes a fail to start, HOT!

Since this is 1998, you might still have ignition spark plug wires so would a timing light be an option or is it not?
I don’t know what other means are used to check for live sparks on these cars with coils over the plugs?
What can you do but lay a bunch of neon bulbs over the top of the engine and look some glows?
Like checking for a microwave spread pattern?
I know, a AM portable radio! (:- ) the RF static pop!

I can understand the laziness to dig into the top of these plastic capped engines of today to access those spark plugs.
I’m not real great in pulling those of my own 240 red blocks and their right there! (:). But they can give up some very definitive information, in their stories they tell.
Gas Fouling or not?
The other choice is getting caught kneeling and smelling up the butt of your car! (:) 🤥(:-)🤫

As far as the hesitation happening that could be a myriad of things going on with breathing of the engine and the dealing with abrupt fuel mixture changes since there no load on the motor.
The fuel management program is not going to match up to such conditions so repetitive, especially with a used exhaust system of this age.
The adaptation of “adaptive learning” adjustments, in 1998, was still on drawing boards for the most part.
This issue might be what DEALERS say, “ oh, it’s a characteristic of the car.”

You might have to accept, that it’s Now Acting, like the humans that made it? (:-)


Phil