Any solution to my car stalling or not starting. Getting worse last 3 years on 1999 Chevrolet Monte Carlo

Car stalls and used to restart right away. Now it may take hours or overnight to restart. Got worse over last 3 years. No codes. Left at mechanic 3 times for a week each time and they could not duplicate the problem. Replaced fuel pump and filter. Appears it might be electical as I could not get spark form coil when cranking engine.

Asked by for the 1999 Chevrolet Monte Carlo