I have a 1997 cherokee sport 4.0 that started running rough and shaking. I replaced the oil filter adapter orings and that took away the codes i had but it still runs rough. Theres a slight ticking noise coming from right side of engine and a small amount of smoke coming out from valve cover after running for ten minutes or so. There are no codes at this time. Any help is greatly appreciated.

 

Am I understanding correctly in that you had codes, fixed the o-rings and now no more codes?

Let's start with the basics - full tune up:

1. Ignition system: inspect your plugs, wires, cap, and rotor. If there are any deficiencies, replace them. Champion copper core plugs gapped at .035.
2. Oil, oil filter, and air filter.

That covers the air and fire aspects of combustion. Now let's talk about fuel. Good fuel pressure? Perhaps a fuel filter is in order, along with some fuel injector cleaner in your next tank of gas.
How's your mileage? Any severe decrease from before it started running rough?

 

Yes that is correct, i had codes but now dont. I just replaced the spark plugs but not the wires or cap n rotor. There is 240,000 miles on it and it's been fine until now. The plugs that came off, there were two of them that had a huge gap because the metal prong had worn all the way down.