bronco wont idle?

[mash]

i just swapped in a new motor and it will run as long as your reving it or holding at a high rpm but will not idle? My guess is carburetor issues, but im wondering if it was somthing i messed up in the timing while changing the distributor? if timing was way out would the motor even run? Any advice or help would be much appreciated!
thanks
josh

 

[NYLES]

if ya think its timing restabb it take 10 mins, yea itll run with timing all messed up

 

[travis77]

that was happening to mine. the idle speed screw was too far out. What carb?

 

[jw0747]

check timing first then move to carb