89 2.8 idling problem

I have an 89 cavalier z-24 2.8 auto. I replaced the IAC, pressure regulator, fuel filter, purge solenoid on top of the charcoal canister, plugs, wires,ignition module,o2 sensor,and air intake temp sensor and computer. Checked the TPS, MAP, fuel pressure, and oil pressure. My problem is the car wants to idle up and down under braking or when I let off the gas. Its driving me insane I really like my cavalier convertible (I bought it for $250 from a guy who couldnt get it started) and I am at my wits end with this problem HELLLLPPP!!!!
Thanks,
Bill

I found my problem I had to teach the computer the new throttle position sensors position. I guess thats what youd call it

Isn't that something? I've been having the exact same problem with my 89 z24 convertible -- for the past 3 yrs. it's been a perfect car but like you said this has been really getting to me --- how specifically did you teach the computer the new throttle position ?