06 liberty rough idle

[06liberty]

Just bought a 06 jeep Liberty. Has 52,000 (not diesel). Has rough idle when stopped at a light. RPM sitting at 500 when stopped. If put in park RPM at 700-750.
*engine light on
Dealership visit 1: replace spark plugs,
*highway travel 1200 km
*engine light on
Dealership visit 2: Blew out carb build up
*in town driving and highway trip 600 KM
Dealership Visit 3: they told me spark plug was dirty with carb tried to adjust the idle
*worked okay for about 10 KM then same issue arises.
The jeep idles so hard the jeep shakes, and now when going to a stop the jeep jerks when at about 8 km/hr until I come to a complete stop. The dealer is telling me that this is normal for a jeep and not to expect it to run like a Cadillac. I have gone on numerous road trips in a Jeep and no one else I know has ever had this issue. I know how normal jeeps are and this is far beyond what "normal". What do I do now?

 

[SteelHeadz]

What was the DTC when it was scanned?. I'll go ahead and assume that it's in the P0300 dtc since the sparkplugs was in question. The 3.7 liter you have may have other issues with a misfire but not nescessarily a fouled plug. Let me know what the DTC is and how consistent is it to a specific cylinder.

 

[06liberty]

I am going to the dealership right now and asking for the code reading. Will have more details in about an hour. Dealership still insisting it is normal. But Jeeps do not send out codes if all is working good.