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Have a scan done at autozone or O'reilleys to get the diagnostic trouble codes read, and go from there. Anytime the light comes on when running, the computer has set a trouble code. It will direct you to the problem. Have the fuel pressure tested to see if it is the fuel pump. If fuel pressure is correct, it may be your catalytic converter. But get the codes first-they should point you in the right direction.
it could be the EGR valve or Mass airflow (MAF), you can check if its MAF by disconnecting it for a test run and see if it loses power then. do make sure you connect it back after checking.
Have you checked out your air filter? Has your 02 GMC Envoy had a tuneup? Also you may need to replace your fuel filter as well. (especially if you drive in a dusty area) A vehicle as new as yours still needs preventive maintainence to keep the "new" parts working properly. While this won't stop the components from eventually breaking down and causing you headaches, its still a good idea to check these things.
when the check engine light comes on it indicates the engine control computer (called the PCM) has detected a failure in the electronic fuel injection or emission control system, the 1st phase of finding out what the problem is being caused by is to run a OBD2 electronic engione control fault code test, this can be done with a generic code reader avail from any auto parts store, you can also get a free fault code test run at any Kragen auto parts or Autozone, other so called discount auto parts stores do this for free as well, the code will have a definition attached to it, it is likely you have either a fuel pressure problem or a MAF (Mass Airflow) sensor failure, but both of these repairs are expensive so don't guess get the test run.
When I see all these codes i instantly think of two things. Vacuum leak especially intake manifold gaskets and Mass air flow sensors. Spray the engine with carb cleaner when its running and see if you get it to rev up,run rough or run different. Next unplug the MAF and drive the car, see if it runs normal.
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