I have this problem that started thursday night. I hope someone knows what this is. The temp gauge doesn't move past COLD. It makes the engine idle at 1500-2000 rpms. someimes it will move after 20 miles of driving, this morning it was the same way. When I coast to a stop, it just idles up at around 1500 rpms. I disconnected the battery for about an hour to try to reset the computer, but it did it again. Has anyone used royal purple "ICE" coolent? I wonder if that is causing it? 