Ok guys, I did a search and couldn't come up with anything conclusive. My check engine light comes on only when I am driving under load and when I am on the gas pretty hard like going up a hill on the highway. If I am driving around town it does not come on unless under hard acceleration. I pulled the codes and I get a Code 13 and a Code 43. IDK how I am getting code 13, as the O2 sensor is hooked up and it is working as far as I know, because I put headers on the truck and when I didn't have the sensor in the check engine light would be on constantly. This has got me stumped. Any help would be greatly appreciated. 
