96 Automatic GT, 155K. After replacing spark plugs, wires, radiator, thermostat, valve cover gaskets, fuel filter and the IAC, I started my car back up thinking great, finally no more issues!! Well, because my car hates me, it’s now got some idle issues I can’t figure out. While driving, after the car warms up and I hit about 40mph, once I let off the gas the rpms will drop suddenly and then come back up. In addition, while sitting at stop lights, it idles extremely low, usually about 500-750 rpms depending on how it’s feeling that day. If I turn on the heat while at a stop, the car will force itself forward a few inches no matter how hard I have my foot on the brake and act like it’s going to die. It’s driving me insane and I read that it could be because of the IAC, but I just replaced that because of other idling issues it was having before. As far as I’ve seen, it is also not electrical because I have not seen my lights dim when the rpms drop. Any help would be much appreciated.. there are about four of us that have no idea what is going on with it.