1991 Buick Century 3.3 Liter V6 hesitation

problem? 1991 Buick Century 3.3 Liter V6
I have a 91 Buick Century 3.3Liter v6.The problem occurs when the engine gets warmed up,say like 15 minutes of consistent driving.When you stop and step on gas pedal to drive,the more gas you give the slower the car moves.There is hesitation for a while then suddenly the car takes off and runs okay for a while then process repeats itself. The car does not stall but will slow down every time you give more Gas. When you stop and wait for 10 minutes for the car to cool off, the car accelerates just fine of 1/2 a mile then same problem occurs repeatedly. There is NO 'Check Engine' alarm. I replaced TPS(throttle position sensor),fuel pump, ignition coils & module,spark plugs,(ECM)Computer ...STILL THIS HAS NOT HELPED CLEAR THE PROBLEM. I NEED HELP... Any good hearted Master technicians willing to Help me? PLEASE ADVISE !

Im not a master technician, but i might be able to give you some advice about this problem. I have a 1993 Buick Century with a 3.3L V6 engine that once hesitated during warm up, and idled a little jumpy sometimes after a cold start. I replaced the idle air control valve, and that cured the problem. The idle air control valve is about the size of a deck of cards, has 3 prongs, and is mounted on the top of the throttle body. The 3 prongs on the idle air control valve are labled ABC, and its part number is AFH5OM-02A. Thats the part number i got from my car, but im 99 percent sure its the same part as your car. Make sure you remove the screws carefully with a good screwdriver, and make sure the o ring is intact when installing the new one. I would like to say that this is a common part to be gone from junkyards. It took me awhile to find one in the yard because most of them were removed. GOOD LUCK!