once in a while when i start my 90 5.0 it will crank over try to start then stall out...then ill try again n it will turn over for about 3 sec n then fire up some times real low then idol up n some times high then idol down...but wen it does this it smokes from the exhaust wen it starts...
it has a new motor in it with 3300 miles on it so i dont understand y it is doin this..could it b not enough air or fuel gettin to it

any helps appreciated

 

go to www.muscularmustangs.com, maintenence section, and read the rough idle section , it gives a step by step to testing and fixing your idle and related problems.

 

sounds like your running extremely rich.

If that smoke is black, check ur plugs and make sure theyre not really blackend. And as 7upedition said, read that link