#1 - I have no experience with the AMS PMS, so I have no comment. I do understand it has a hefty price tag though.
I have a Moates QH with my setup. I've also purchased the software license for the Binary Editor and Engine Analyzer. In the least, you'll need the Binary editor for making changes.
You should definitely acquire the Engine Analyzer for capturing datalogs of your runs. This will help you identify areas for improvement.
Before you consider an DIY computer/ECU tuning solution, you really should educate yourself on all that is required and involved.
Go Here:
EECTuning.org • Index page
Read the FAQ --- Search for the article:
Things to know BEFORE buying a TwEECer or Quarterhorse
It's been a long time since I've read that article, but you're going to spend quite a bit of money to even get to a point of capturing data logs. Wideband O2 sensors are not cheap, Moates QH card, additional 5 position switch, Binary Editor Software, Engine Analyzer software, weld-in bung for WB-O2 sensor....yada yada yada. There's a fair expense and a little time required just for reaching a point to begin using your DIY solution.
The next step is to "KNOW" what to change... and to what value. There is no quick support line to call...share your datalogs with...or receive recommendations. The forums are good for seeking help, but you cannot count on them.
The long & short of this is that there is a learning curve when performing this work on these older computers. It takes a lot of reading and understanding before you should initiate change.
I would offer a 3rd option to you... and that is to get your car into a chassis dyno where a qualified technician can burn you a chip. A good shop will also go out for a drive around the neighborhood to ensure that your engine maintains some sense of civility for street driving...and after flogging the engine, she returns to her street manners properly.
Yes...you'll need to do this for each "substantial" change you make to the engine. My local guy charges ~$300 for a tune. You're going to spend much more than this for all the DIY equipment you're going to need...hell, I spent more than $600 on all my stuff.
In short...you mileage may vary. But unless you're prepared to get into understanding the Ford ECU in your car, then you should probably consider having a Pro burn you a chip on the Dyno.
((Do Not order a custom burned chip online --- penny wise, but pound foolish).
Just my thoughts... which are subject to errors.