When my ECU fried, the Monty had been idling and running fine. But when I tested the ISC it was open on a couple of the coils. Some guys have gotten their vehicles to idle OK by unplugging the ISC, then manually adjusting it to get the right idle. I don't know how this affects the ECU, maybe someone else can chime in and discuss that.

90 Montero, 2dr, AT, V6, LSD, AC, KYB shocks, bouncy seat, 182K miles, JDM engine, 87 Starion seats, tow hitch
http://www.geocities.com/idahojack03/Index