Need Help with a misfire issue

Hi I got a 2000 Jeep Cherokee with a 4.0,
it was running rough and I decided to replace the plugs as they were past due for replacement. I tried the E3 plugs but then it wouldn't start, it finally ran, and ran strong but began to stall here and there then ran really rough.
I put the code reader on it after it threw a light and it said that plugs 5 and 1 were misfiring.
I replaced the coil bar and put OEM plugs in it. It starts consistently but still runs rough, it says that now cylinder 4 is misfiring. I don't get any codes for emissions or fuel injection issues.
Not sure where to go from here, I didn't replace the egr valve as I didn't get any emission code.
Any ideas?

1. No EGR on the Jeep 4.0 after 1990.

2. NGK V-Fire plugs are specified for the distributorless ignition 4.0 engines.

3. Pull the fill cap and check for coolant contamination in the oil. Use a bright light and look for a head crack between cylinders 3 and 4, you should be able to see it through the fill hole.

Post up what you find.

joe_peters said:

1. No EGR on the Jeep 4.0 after 1990.

2. NGK V-Fire plugs are specified for the distributorless ignition 4.0 engines.

3. Pull the fill cap and check for coolant contamination in the oil. Use a bright light and look for a head crack between cylinders 3 and 4, you should be able to see it through the fill hole.

Post up what you find.

Click to expand...

Thanks for the reply, I hope to God it's not a head issue, like I said the two cylinders stopped misfiring and then 4 started.
A head issue usually means big dollars...
thanks again