87 SS stalls while driving
 

Last spring ..Been firing it up in the garage all winter,..then no spark! Installed new cap, rotor & module. Coil seems good... all MSD components...ran great all summer until a month ago when I was getting on the gas....it was missing,...the tach was bouncing and flicking up n down! It recovered,,, and I got it home no other issue. Took it out few times since...no problem, last week it shut off while driving and was at lowest RPM and sputtering...and shut off! It fired back up no problem and I got back home! I checked wiring as much as I could. Electric fuel pump and safety oil pressure switch.
Anybody got an idea whats next to check....ignition switch?