Cherokee Sport 4.0

[BBlockLX]

There seems to be a few of you that know quite a lot about jeeps, so I was hoping you could point me in the right direction on mine. I have a 95 cherokee sport with the 4.0 and sometimes it runs rough at start. After feathering the throttle to keep it running it seems to be fine. Well, yesterday it blew the muffler apart getting it to run. I was going to change the cap, rotor, plugs, and wires today, but I don't know if that will fix it. Thanks!

[Fraser]

how does it run after you tuned it up?  does it idle ok?

[rebelryder]

i would go ahead and tune it up to eliminate some stuff. then go to the O2 sensors. mine did this when the O2 sensors went bad.

[Disturban]

Also clean EGR valve or replace it with a new one. If it is sticking it will cause those symptoms.

[hot rod heep]

o2 sencer    mine did thet   bad wire in the o2 sencer

[BBlockLX]

This is probably gonna sound really stupid, but if it was the o2 sensor, wouldn't the check engine light come on? Because during all the rough running, it hasn't.

[Fraser]

This is probably gonna sound really stupid, but if it was the o2 sensor, wouldn't the check engine light come on? Because during all the rough running, it hasn't.

so the tune up didnt change anything?

[BBlockLX]

Oh no, the tune up (so far) was the answer. I did the plugs, wires, cap, rotor, and replaced a couple rubber vacuum pieces and it fired right up and ran like a champ. Only time will tell, especially since it didn't do it all the time to begin with. 

[jratliff]

check your iac  sensor