94 z28 hard start and stalling

i have 94 z lt1 and it starts hard and stalls now and then,and trips no codes?it acts like the timing is sluggish to advance and pops through intake at first then reves up.checked spark seams ok.i had the chevy garage evaluate it and they said distributor was bad,so i tore it down replaced cap rotor wires water pump ingnition moduel,only thing i found wrong was 2 plug wires were off and rotor was bad rusty in dist.i hope someone can steer me how to fix?

the optispark distributor on the LT1 is known for being a gremlin hole, you said you did quite a bit to it, but the problem is probly that you need a WHOLE new distributor, there is more to it than the rotor and cap, the distributor its self goes bad. i would reccomend putting a whole new unit on and tossing the old one, minus the new parts you just put in it. being a chevy tech, i would go with what the chevy garage told you, and put a new one in. these go bad alot, and int a pretty good possiblity that the guy who did the diagnosis has done quite a few in his time at the garage, and is giving you his best advice on your problem.