Rodney went above and beyond working on our 1993 Buick LeSabre.
The auto had a start run briefly then stop and would not restart.
Rodney replaced the suspected (code 18) part crankshaft positioning sensor, the crank pulley.
Auto does not even start now.
There could be other potential issues as is the case with the early mid 90's GM autos.
There could be other suspected other parts and issues here.
Though I do believe that your mechanic should send someone to further investigate this problem at no charge, after all the car did start now it does not!