help needed
 

Just got my jeep and it works great but it has one issue that needs fixing when i start it it runs really crappy sputtering and just bad but withing 10-15 seconds the check engine light comes on and it all the sudden runs 100% perfect idles great and runs and drives as long as the check engine light is on but when u first start it its really bad can someone help me with this

i see that i posted on grand cherokee spot can a admin please move it to the correct spot