camero rs 1997 starting issues, smog issue on 1997 Chevrolet Camaro

car starts fine , but after sits for 10-15 min and go to restart its ruff, rummbling and wont start until it sits at least 45 min. then starts right up. having issues clearing trouble codes 171, 174. now new code 0302. Ive changed throttle sensor, mas airflow sensor, fuel filter, oil filter, air filter, flushed cooling system. cleaned egr valve, pcv valve. checked for vacume leaks none...

Asked by for the 1997 Chevrolet Camaro
Plugs and wires? Fuel pressure readings?
3 more answers
Plugs and wires? Fuel pressure readings?
Needs to be seen by a shop that look at the datastream. Did the intake get smoke checked? Now you have a misfire in #2. Spend the money and have a shop diagnose it. STOP throwing parts at it!