* A faulty fuel injector
* A bad spark plug or wire
* A problem with the cylinder head gasket
* A problem with the piston or rings
The high RPM at stop lights could be caused by a problem with the idle air control valve or the throttle body.
To diagnose the problem, you will need to connect a scan tool to the vehicle and check the live data. This will allow you to see what the engine is doing and identify the source of the problem.
Once you have identified the source of the problem, you can then repair it. If you are not comfortable performing this repair yourself, you should take your vehicle to a qualified mechanic.
Here are some additional tips that may help you resolve the problem:
* Check the fuel pressure and make sure it is within specifications.
* Check the spark plugs and wires and make sure they are in good condition.
* Check the cylinder head gasket and make sure it is not leaking.
* Check the piston and rings and make sure they are in good condition.
* Clean the idle air control valve and throttle body.
If you have any questions, please feel free to ask.
