I still haven't figured out what is causing the jerking at low RPM. It is effected by load like when the A/C is on. I replaced the IACV, I thought that would be it for sure. No luck. Distributor, plugs, wires are new. Fuel pressure is good. I replaced a couple vacuum hoses that were starting to crack. I checked and cleaned MAF sensor and throttle body. Could it be EGR, TPS? I don't have any codes. Is there a way to test the ECM?