I have an elantra 2009 Se, my car goes down to 600 rpms and shakes when I stop. It has 186.000 miles. I replaced the battery, I already replace the IAC, spark plugs, spartk plug cable, New alternator, new belts, new timing chain along with the water pump, I replaced the maf, I replace engine oil every 4 months, I replace the purge valve, new air filter, replaced transmission oil, New suspension struts and shocks. When I idle the car at 950 rpms the car works fantastic it won't do it automatic. The lights go dim and the ac doesn't work right at 600 or 650 rpms. please help me it's ver frustrating I don't know what else to do. thank you so much.