Engine Performance problem
1989 Buick Riviera 6 cyl Front Wheel Drive Automatic
Mar Riv starts with a high idle. Sometimes it comes down, and sometimes it just stays and I have to turn it off and start it again and again until it goes down. I know it's not the IAC motor because that's brand new, as well as the Throttle Position Sensor. There are no trouble codes other than the Camshaft position sensor codes, which has been there for years. Also, it does backfire occasionally. Any other ideas what it could be? I was thinking maybe the intake manifold gasket.