Laura - didn't want to highjack the other thread and this is an interesting topic that deserves some discussion. Here's your last comments:
" Jharger, I have a 1994 XTL Explorer automatic, as my daily driver which has a lack of power problem and I just got this 1993 XTL Explorer 5 speed Manual, which needed a whole lot of body and interior parts ( swapped the parts from my 1991 EB Explorer ). I got it all back together except for gear shift **** and the right ecm. I'm using an ECM out of a 91 automatic explorer til I get one for this manual explorer. "
Gear shift **** is an eBay item. i suspect you're not too worried about that. The 1994 we can talk about later.
If both your 1991 and 1993 trucks are Fed emissions, the 91 PCM probably works OK in the 93. Neither year had EGR's (from what I've been told - even though the schematics still show them). And both years are multiport fuel injected (MFI). The later model PCM probably has slightly better A/F mix and spark curves programed because it seems Ford got a little better on this every year.
In 1991 I think a BAP (barometric amoshpheric pressure) sensor was used but then went away in 1993. You can check your trucks to find out but I wonder what type of CEL code this would throw.
In 1994 a TSB came out that updated a bunch of PCM's - can't flash EEC-IV's so they got a new part number and swapped out at the dealer. It was a minor update to help the car run a little richer at cold idle to prevent it from stalling when you put it in gear. There was only one Fed manual PCM affected...and I don't know if this will help you since you don't have the original 93 PCM so you don't know the part number (or maybe you do). The old one was F37F-12A650-YB replaced with F47F-12A650-CMA. If you can use this new one, it gives you another part number for your search.
Now with the tranny difference, are you getting any transmission CEL codes? Isn't there a 3/4 shift solenoid signal that the auto PCM is looking for?
Now back to your 1994. All Explorers that year got EGR's and SFI (sequential fuel injection). So it's easier to talk about this one as it's more generic than the mix match of the earlier years. Obvious MAF cleaning, tune up stuff, make sure the EGR system is working right...all will help the power loss. What symptoms and any PCM codes on this one?