Engine Mechanical problem
2002 Chrysler Concorde 6 cyl Two Wheel Drive Automatic 176500 miles
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serviced at reg intervals. drive 100 miles a day. engine running ok. No codes at this time. change plugs to improve mileage? three weeks get po300, random missfire. plugs are bosch platinum. change boots, clear codes ok for one week, now code 300 and 152. change plugs to champion platinum and clear codes now code 300 and 152. Can fuel system set code 300? what am I missing? thanks bobbyg