hey i just got my car up and runing its a 1986 mustang 5.0. I went to pick it up and the guy says it has surging idle and when it sits and warms up its a litle high. He said it because of the iac valve is from a 90 mass air car. I put in a E303 cam with 1.7 rockers. IS the surging idle from my car being speed density and need to be switched over to mass air?