how to check for carbon plugged hoses connected to egr valve?

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what my car is doing: HARD TO START(sometimes have to hold key over for 10sec before it finally starts. LACK OF POWER GOING UP HILL STALLING, MISSING,& BACKFIRES RUNS ROUGH.( punched hole thru catalytic converter. i have replaced the o2 sensors myself, put in new plugs and wires, new maf sensor, check pcv valve myself . most recent i put in new egr valve. My car is pulling a p402 code. had someone check to make sure its opening and shutting. i read somewhere that the hoses coming off egr valve could be plugged. just not sure how to do this myself. i realize my issue could be a number of things like TPS SENSOR,KS,CPS,MAP SENSOR, FUEL INJEC DIRTY OR STICKING, CAT CON, O2, BAD PUMP(which i dont know how to check and most recently someone told me maybe its incorrect timing. I JUST DONT KNOW WHERE TO START. YES I AM A GIRL. PLEASE HELP oh ya it does sound fuel related when lack of power going up hill. I also live on top of a hill.