need some help plz
 

I am thinking that one of my cylynders is gone on my 03 but not sure it seems like it has less power but could also b because the tempatures at night i was wondering if it would throw an engine code if i was out a cylynder and im not blowing any white smoke it just is drivng different so wondering what the signs of a blown cylynder or piston is all help is appreciated thank u

RUN a compression test this will tell you all you need to know.

^ I agree, I would check fuel side first though, fuel filter, lift pump, injector returns/fuel tube nuts