First time poster here, Hi all.

98 8 zj v8, Stumbles when idling. The stumble is not consistent, sometimes it is every 3 4 seconds, other times it might be a minute. The stumble is very sharp, no noted RPM drop.

The feel of it leads me to think it may be electrical. Had the codes pulled and got a missfire on cyl 8 reading. Then last week the car seems to have fixed its self, boy I hate things that self fix (or not).

Any idea?

 

Check your spark plug wires, distributor cap, and the spark plug itself. Look for carbon trails, cracks, or anything that might be shorting that cylinder itself. Even a larger than normal gap on the plug will cause an intermittent misfire. Look at the spark plug boot where it goes over the plug for burns from arcing. Check if the wire itself is shorting on something. I've seen tiny holes burned in wires where they laid in the trans dipstick tube.

 

x2
my buddies 94 dakota (same engine, 5.2) had a multiple cylinder misfire. we changed the plugs, wires, cap, and rotor and it ran like a top after that.

 

IMHO, if you buy a cap, buy the premium one with brass contacts. Aluminum contacts burn away and corrode to fast. Rotor likewise.

 

For V8 ZJ's experiencing misfire this might be of help. >->TSB 18-48-98 5.2L misfire fix