As a diagnoses suggestion, start its engine, let idle, lift its hood and with a simply garden hose with sprinkle spray, put water all over the engine. Move slowly. Actually, it's best to perform this diagnoses trick at dark time - to see any micro sparks / electrical arching. If the engine suddenly hesitates, displays some sparks or stalls, you found the problem area. If wondering, my previous Safari van did the same thing. re: It would run rough - like it had bad gas. Did the water sprinkler trick at dark time and the mechanic discovered bad spark plug wires. Note: Don't spray water directly into vented alternator unit or other extreme sensitive electronic areas. Only need to lightly spray water - to see if idling engine RPM / behaviour changes.
Hope this helps...