I have a 1993 mustang LX with the 5.0 in it. The motor has been rebuilt by the person that i bought the car from. It has a 303 cam gt-40 heads and 75mm throttle body and EGR plate and i cannot get it to idle correctly. When i bought the car it had the stock throttle body on it and the guy said to just change to a 75mm. Well i think he was wrong as mush as i hate to say it. Does any one have any ideas what i can do.

 

Did it idle correctly with the stock TB?
When you installed the 75mm TB did you set the idle and TPS?

 

What Mass Air Meter do you have? What size injectors do you have?