Codes P0301,P0507 2001 SL1 Help

My check engine light has been on for two years. went to three different shops, did repairs, next day light on again. replace something in ignition, fuel pump, tune up. Now given codes P0301 & P0507 andcar failed for emissons. What should I start with to get this light off and problem resolved? Codes aren't very specific. Help :runaround:
Suzanne