I have a 2003 Dodge Ram 1500 5.7 4x2. The RPMs drop from 650 to 500 at a stop light. I have no engine light, no error codes and the truck runs great. When I get to a stop light and the rpms drop, I can lightly tap the accelerator and the RPMs go back to normal, I can put it in neutral and the rpms go back to normal, or I can turn the AC on and the RPMs go back to normal. Any of those steps work. I can keep the AC on or just regular air and the rpms maintain normal levels. The local Dodge dealer has changed the Throttle Body, Camshaft sensor, crankshaft sensor, accelerator control, torque converter, spark plugs, MAF, and battery, so far nothing has repair this issue. Can this be an electrical surge? I don't know what else to check?