'91 2.3l will have the dual coil set up and EDIS-4 module on the front side of the intake manifold.
The way these distributorless systems work is not to different than the older TFI system.
PIP = Profile ignition pickup, this is the signal for when each piston is at TDC and especially when piston #1 is at TDC.
PIP signal starts at the Crank position(CKP) sensor on the crankshaft, CKP reads a wheel on the crank that tells it when #1 is at TDC and also each 10degs of rotation of the crank shaft.
This signal is sent directly to the EDIS-4 module.
EDIS module is hooked to the dual coils and fires the coils(spark plugs) based on the PIP signal.
The PIP signal is also passed on to the computer so it knows when to open fuel injectors.
The computer has other sensors, the main one for this application is the TPS(throttle position sensor).
When you put your foot down on the gas pedal the computer "sees" this via the TPS sensor
Computer adds more fuel AND tells the EDIS module to advance the spark so you get instant power.
The computer "talks" to the EDIS module via the SAW wire, SAW = Spark Angle Word
This used to be called SPOUT(spark out) on the TFI system.
The SAW signal "tells" the EDIS module when to advance and retard the spark and by how much.
EDIS module can run the spark all by itself, it doesn't need the computer to do this, BUT....
If your acceleration is sluggish then EDIS is not getting advanced warning of when to advance the spark, it is adjusting spark timing solely on RPM, which maintains speed but there is no "power".
So if PIP signal is not getting to computer then there can be no SAW signal coming back from computer, so lower power.
Good read here on the EDIS system and pin out diagrams if you want to check wires: Ford EDIS technical information