Q: idle speed on 1990 Jeep Cherokee

Your idle speed, timing, and spark plug gap should be on the emissions sticker under the hood. If you think the idle is low, check your throttle body for carbon buildup. I cleaned the throttle bore and butterfly on my Wrangler and it helped quite a bit. Spray a towel with cleaner and scrub the bore and blade edges. Mine was really caked on there. Don't spray directly on the throttle bore because this can damage the sensors on the throttle body. hope this helps