1998 Dodge Intrepid 2.7 -- After running for 30 minutes, the car starts and runs rough. Driving up to temperature it runs fine. After sitting for 15 minutes or so, when starting it runs rough and will shut off, but after revving the engine it will smooth out. Have changed the cam shaft sensor and crank shaft sensor and recently replaced the spark plugs. It stills runs rough. Had it checked at Autozone and says there is a misfire or O2 sensor.

You need to replace the o2 sensor. did they specify which bank? it should have said bank 1 or bank2 is your check engine light it should be. the crankshaft sensor most likely was'nt bad or else the motor would'nt start. running rough may have been the camshaft sensor, was good guess. but guess was'nt right.,if auto zone told you bad o2 sensor i might say ok, but have them run the diagnostic again to make sure it's not the idle control sensor just to be sure.. hope this helps!!

It sure sounds like you have an EGR problem. This valve controls the flow of unburned exhaust gases and re-routes them too the intake to be re-burned. This valve is usually open at highway or cruise speeds. Not usually open at idle. If this EGR valve is open at idle, you get a rough running for sure just like a mis fire and will smooth out as your speed increases. I would get that checked out and if faulty, replace. Please keep in mind that this part is quite expensive new, but it is electrically controlled. good luck!