Starting problem 1994 Ford Ranger pickup

Smetimes when I try to start my 1994 Ford Ranger pickup after it has started and run fine. I will try to restart engine will turn over will not start, wait 10 to 15 minutes and it will start wright up.Shop cannot find problem

The infamous Ford TFI ignition module can cause this problem. [ Ford denies that their ignition module ever had a failure rate any higher than any other car maker’s.]