I have a 1968 mustang with a 289. I recently replaced the distributor with a mallory unilite,plugs,wires,battery and I rebilt the carb. The car starts good and is responsive cold, but when I run it awhile and I come to a stop it acts like to wats to stall. some times it does stall but restarts everytime. I also notices a slight what seems like a surge when in gear. Any Ideas?

 

This sounds like the carb could be a little lean.It starts and runs fine when cold but as the engine warms and the choke opens,the carb leans out to the point where it stalls.Start with the idle circuit and only change one thing at a time or you will never figure the problem out.
The float could need an adjustment also.