1995 Chevrolet 454 TBI engine starting problem

Not sure what level of training the mechanics had but they sound like parts changers!
Yours is a straightforward system that is easy to diagnose, fuel or spark or both.
Since they "repaired' the ignition system it would seem that the problem is fuel.
Fuel as stated, relay and/or pressure switch.
Also could be fuel pump (in tank), pump wiring, fuel filter.