CASANOVA86

Hey there fellow SC enthusiasts, the problem I'm having now with my 92 SC300 is that when I throw 2nd & sometimes 3rd & gun it the car like hits fuel cut or something it just boggs out for like 2-3 seconds then it picks up again but when I'm just cruising its good. I changed the cap, rotor, spark plugs, spark plug wires, intake, fuel filter, some computer there that my mechanic put in IDK what else to do. Does it have anything to do with the car being automatic & switching it to manual? It still has the auto ECU does that matter?