Oil pressure in my 2002 Envoy keeps dropping, has happened more than once. Took to dealer, told it was oil pressure switch, I replaced it. Same thing happened two days later, took back to dealer, said it was vct solenoid, replaced it, same issue is happening again. Took back to dealer, now they are saying it's the cluster and needs to be replaced for 500.00 dollars for part and one and a half hours for labor... After buying it they say it might not be the problem .. Need help and answers....