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Check the butterfly flap in your throttle body and make sure it's clean of carbon buildup. The TPS ( throttle position sensor)on the right side of the throttle body picks up info and sends it to the computer. You can check reference voltage at the plug with a pigtail adapter and good meter. And last the IAC ( idle air control) that's on the bottom of the throttle body has a pintle that opens and closes that can get carbon build up and not work right. It opens up at idle to let air in when the butterfly is closed in the throttle body.
IAC needs to be taken out and cleaned. Do not twist the plunger. Just use some high quality sensor cleaner, and soak the living crap out of it. Then let it dry. Then put it back in.
If it fixes it,which it probably will, then go by a DENSO or AC DELCO. That way you get another one to last 15 years.