erratic idle.

My 86 mustang (i'm not so sure on the engine size yet. I know its a 4 cyl) won't stay running when i first fire it up. the idle on it goes from 250 all the way up to 1000rpms when first starting it. Even once its warmed up it still idles erratically from about 600 to 1000rpms. I've never had a car with a carbuerator and know next to nothing about them. Does anybody know what might be causing this problem and how to possibly fix it?

I've already changed the air filter, spark plugs, oil, ect. Just the typical tune up. None of that seemed to help though.

I thought '85 was the last year for carbs, but I could be wrong. If its EFI then check the TPS & IAC. If its carb'd then you need to rebuild the carb.

I could be wrong but I am almost positive that the last year for carb'ed mustangs was early 84 or early 85.

I just know if you look up a distributor at a parts store for a 1985 mustang 5.0 its vacuum advance. Therefor carb'd.

85 5-speed v8s are carbureted and the automatic v8s have CFI which is essentially worthless, but i have no clue about the 4 cylinders. possible the original poster is mistaking a TBI or CFI style intake for carb?

i agree though, if its EFI you need to ID and locate the Idle Air Controller (IAC) and remove it so you can clean it out with carb cleaner or even brake cleaner. probably not a TPS issue as those tend to make the engine idle much higher, usually around 2k-2.5k rpms.

edit: i just looked it up and it seems the 4-cylinder in 86 had a 1 barrel carb! "1986 Ford Mustang 2.3L 1BL"

there's some info about adjustments etc at http://www.autozone.com/az/cds/en_us/0900823d/80/16/6a/9d/0900823d80166a9d/repairInfoPages.htm

thnx for all the help. i think ive almost got it fixed now.

86 4 cyl mustang came with a carb usually a one or 2 bbl.