I've had a problem with my O2 sensor and air filter causing my 1998 firebird to misfire.
Carbon buildup can keep a motor from firing and cause an engine to stall.
A vacuum leak is one possibility.
If it is out of order, yes.
There are pages and pages of things that can cause a check engine light. You need to have it checked with a scantool. Then the code can be diagnosed and repaired.
Reduced engine power, on your 2005 Pontiac Montana, can because by several things. The most common cause of reduced power is a lack of fuel.
the engine is running checky after starting
It might cause the "check engine" light to come on.
There are pages and pages of things that can cause a check engine light. You need to have it checked with a scantool. Then the code can be diagnosed and repaired.
Worn spark plugs would cause mis-firing or non firing cylinders, both are no good for the engine, replacing the plugs may stop the knock (Could also be a different problem) But you should replace spark plugs as soon as possible.
get a tune up it could be the spark plugs not firing right or clean ur fuel injectors
A 2001 Pontiac Sunfire 2.2 engine is a zero tolerance engine which will suffer catastrophic damage should the timing system fail. Because of the tight tolerances inside the engine, even being out of alignment a fraction of a second can cause the valves to slam into the pistons.
There are pages and pages of things that can cause a check engine light. You need to have it checked with a scantool. Then the code can be diagnosed and repaired.