There seem to be two different issues:
1. Low rpm all the time due to clutching or other issues.
2. RPM fade where the sled will rev to over 8100 rpm and then drop down to around 7700-7900 rpm and sometimes as low as 7400 rpm. They say sometimes it takes a few miles to happen and it is almost like someone is flipping a switch when it happens. The tone of the engine even changes. This issue is not a clutching issue because people have swapped clutches, springs, weights, belts, checked deflection and alignment and it didn't solve anything. Some are saying it is caused by air pockets in the cooling system, tps settings, exhaust valves not opening all the way or maybe the ecm is running in some sort of protection mode that no one knows about.