At times my speedometer is stuck between 10 and 40 mph when I haven't started moving and when driving moves slowly. other time it's fine or at least I think. It is starting to get worse. I was cited for doing 80 mph when my speedometer was reading 70 on cruise control. My oil pressure gauge is stuck on the high side all of the time.
what is causing my speedometer to start sticking and oil pressure gauge on high on 2005 GMC Sierra 1500
Sounds like a faulty cluster to me. Some clusters will have voltage regulators on the circuit boards that go bad, while others have gauges that go bad. I would have this diagnosed by a dealer level tech that sees these vehicles everyday.