1995 Oldsmobile Aurora Aurora engine

Hello.I own a 95 Olds Aurora.I have had problems with it since the day I bought it. And here in Romania is very hard to fix this kind of car! My problem is with the engine. When I start it in the morning and it s cold it runs perfectly but when it heats up the engine begins to lose power especially when I push the accelerator suddenly. And it starts pretty hard when it s very hot.I changed the fuel pump, fuel pressure regulator, injectors, spark plugs and wires, throttle postion sensor, almost all the parts with the igntion system. And it still doesn t work like ot should. Can anyone help me and give me an ideea. Someone that has or had the same problem. Thanks