So i have a couple things i need help with... first is the car is runin rich, really rich its getting worse gas miledge then my 02 liberty, i jus bought the car and the guy said that he had changed the o2 sensor within the last year so i dont think it is that, i dont have a lotta extra cash so iam trying to pinpoint the most likely cause. the car has an intake, megan header, and 2 1/2" exhaust to the muffler, no cat. also the heater only blows hot air when iam stoped or driving slowly as soon as i go on the highway theres no hot air, any help is muchly appreciated