I have been having a problem with my 2003 Avalanche shifting at 4,000 rpm form 1st to second. Or, if I let up on the gas at 2500 rpm it will shift. It then will shift to third but will run a 2000-2500 rpm while driving. I have been told this could be something to do with the instrument panel or the clutch plate. It is an automatic transmission. Any thoughts?