My normally reliable 1968 Mustang (302) has been simply stalling on me in traffic - most frequently at stop signs but also in slow freeway traffic. Points, condenser, and plugs were replaced and it was tuned-up. I was advised carburetor should be rebuilt. Solenoid was replaced and carburetor was rebuilt. Defective, new solenoid was replaced and it still stalled. The mechanics at the shop where I take it are running out of suggestions about the problem. Any suggestions would be appreciated.