Mike,
I feel for you every time I read this thread, please don't let this setback mar you Pantera ownership experience.
There's a lot of talk about Webers, but you have an 8 stack EFI system, which is infinitely more tuneable than Webers IMO. Haltech is also a great brand and the older versions are relatively easy to tune. There are also a number of Pantera owners who know their way around tuning it. You can download all the software and manuals you need from Haltech's website and may just need a laptop running the older Windoze 98/2000. Floppy disks can be transferred to a USB or like pretty cheaply, but you may not even need it.
The difference in the plugs is likely down to synchronzation of the butterflies and a good synchrometer will help.
One alternative to really enjoy the car for now is to get yourself a Holley 4 barrel and switch out until you have time/money to address the EFI challenges.
Good luck and please stay with it, you will be rewarded eventually.
Julian
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