[redfox1977]

I just bought my first 2.3 4 plug fox about a month ago. The guy I bought the car from put a ranger roller cam and ranger header on it about a year ago. He told me when I bought it that it will not idle well when you first start car and that it was due to the fact that the o2 sensor was in a differant place on a ranger header than on a mustang header and that if I moved the o2 sensor below the maniflold gasket It would stop the idiling problem. Well I havent done that yet and honestly Im curious to know if that could be the possible problem. The timing on the car is dead on and there doesnt seem to be any vacumn leaks. It idles like a champ after driving for about 2 minutes however if it is a warm up issue then why after only sitting 5 or 10 min after a hour drive does it start idiling rough again.. He told me this started after he installed the ranger roller set up. Im hoping someone who has done this mod can shine some light on this for me. I just do not want to start replacing a whole lot of parts if I can get a good idea where to start. Also one guy told me before I relocated the o2 sensor to try using a spark plug fouler and drilling the fouler out with a 1/2 in drill bit and putting the sensor back on using the fouler and that would tell me if the o2 sensor was the problem? sorry for such a long story but i figured the more info i put out the easier it would be to understand what has already been done.
Please keep in mind when responding to this that the idle problem is only when I first crank in the morning and after its sits 15 or 20 min after a run. It idles perfect after driving about 2 or 3 min.
I have asked this on the all ford mustang forum as well but just want to get all the input I can

[blaten22]

Did the guy get it tuned at all?

[OHC230]

"I just bought my first 2.3 4 plug fox about a month ago. The guy I bought the car from put a ranger roller cam and ranger header on it about a year ago."

All dual plug motors had roller cams from the factory, so unless the previous owner installed some kind of performance cam, you could eliminate that as a possibility. The O2 sensor location, while important, would be an unlikely cause for the problem you are experiencing.

I would suggest that you remove and clean the throttle body thoroughly first, with some quality carb cleaner. When the engine is warm, disconnect the idle control solenoid plug (IAC) and set the base idle speed to 850 RPM, by adjusting the idle stop screw on the side of the throttle body. If that doesn't work, re-post.