Suzuki: 1992, 5 speed, fuel injected, 1.3 L Samurai, heater blower, battery terminal

Question
zuk set for 2 years before I bought it. Had no spark, sent ecm off got it back and vehicle started right up. Truck ran good for 1 day and now it interm bug jumps and acts like it is starved for fuel. It can really bog down to where it feels like it is getting no fuel or power at all. Recently noticed that the vehicle was losing power when electrical components were turned on. Hooked battery to a tester that has alternator % readouts. Alternator shows 100% at start up, 85% with heater blower on, 65% with heater blower and wipers on, 25% with headlights blower and wipers. And 35% with only the headlights on. What confuses me is the battery never gets ran down so I do not understand how my alternator could be the culprit.
The loss of power is not restricted to turning on elec. accessories I can be cruising down the road in 5th and all of a sudden it feels like fuel is not being converted to power or the fuel is being restricted to the point where I have to down shift.

Answer
The quality of electrical connection in Samurai has always been somewhat of an issue.
One of the solutions has been to add a 10Ga wire directly from the alt output post directly to the battery + terminal.  Another has been to make certain the grounds are secure and not dirty.
Samurais have had problems operating the starter motor with the headlights on, because a significant amount of power can be lost in the under dash wiring.  Usually, cleaning, replacing connectors, etc is sufficient.  I usually have to do this virtually every year even thought mine is carbureted.  My symptom of marginal connections is tachometer beginning to wave back and forth at a steady engine speed.

The alt is only capable of 45-55 amps max, and it would not be unusual to see a drop in system voltage as more accessories are used.  I have the same issues.  Cleaning/replacing the terminals and connections is still a mandatory annual maintenance ritual.
If you want to solve the voltage issue another way, there are vendors at izook.com who make brackets which will permit the use of a GM alternator with nearly double the output.