I have a 1970 Mustang convertible. All parts are stock for the most part. It does have a new alternator and carburetor. 5 years ago I put in an electric start because the engine was sluggish upon acceleration.  Occasionally it would stall when I would accelerate. I put new spark plugs in, new carburetor and the electric start but haven't seen any improvement. Lately it has started to stall even after being warm and being driven for a longer period of time (1hour plus). It will sometimes stall as soon as I stop. It seemed to be worse when I put it into reverse; as soon as I put it in reverse the idle drops and it stalls.  I have tried increasing the idle and adjusting the timing using a timing gun but it has made no improvement. Does anybody have any suggestions for how I can get it to stop stalling, short of building a brand new engine? TIA!