It's not smart by any means, it just uses very specific programing. The OBD I ecus are like Pentium 2 processors, better than Pentium 1s, and light years above the old MACs, but far short of todays OBD II systems which are like I3, I5, and I7 processors. In short they are night and day.
The reason the 94/95 OBD I ecus are so touchy is because they were programed for a 115* lobe separation, which is different than the 87-93 5.0s which were programmed for 113* lobe separation. Other than that, they adjust pretty well to air flow and fuel needs up to the limits on the injectors/ignition.
They are basic ECUs in that they have general parameters which are used to control the car. These parameters are flexible and not nearly as touchy as modern cars where every little thing is so fine tuned that nothing can be done without adjusting that parameter.
Now with that said, you can't swap ECUs around from car to car. The Mustang uses it's own wiring harness with it's ECU made to run a certain motor with certain parts.
16 Mustang GT - 390 RWHP 370 TQ
13 Mustang V6 PP - 270 RWHP 260 TQ
95 Mustang SVO - 400 RWHP 400 TQ sold
13 Mustang GT CS - 380 RWHP 370 TQ
08 Mustang GT - 285 RWHP 305 TQ sold
99 Mustang Cobra - 280 RWHP 290 TQ sold
11 Mustang V6 - 270 RWHP 260 TQ sold
97 Mustang GT - 190 RWHP 250 TQ sold
00 Mustang V6 - 145 RWHP 184 TQ sold
98 Mustang V6 - 125 RWHP 210 TQ sold