Okay, when the engine is running, it creates a vacuum through the intake manifold. From that, fuel and air is drawn into the engine. Also, many different components are run by the vacuum. If there is a leak, it allows unmetered air to enter the engine which can cause idle problems, poor performance. There are rubber hoses that run from the intake to different places under the hood. Check for damaged or disconnected hoses.
Next, if the check engine light is on, that tells me there is a trouble code stored in the computer. What to do is take the vehicle to a nationally recognized parts store and have them scan it to identify the code. That could tell us exactly where the problem is coming from, and most parts stores will do it for free.
As far as the speedo, that could be a few things. The vehicle speed sensor on the transmission may be bad, the cluster could be bad. The check engine light may be on because of a bad vehicle speed sensor.
Have that check and let me know what you find.
Wednesday, December 1st, 2010 AT 11:20 PM