Chevrolet: stalling in traffic, caprice 9c1, worst case scenario

Question
QUESTION: i have a lt1 96 caprice 9c1 in traffic it stalls , what happens is that when i push on the gas from a stop and  i let off the gas , because i need to go slow, the idle dips waaay down and some times stalls, mostly it stalls. it starts right back up and runs great at high speeds. the stalling seems to be happening right aroung the time it is gonna shift to 2nd gear if it doesnt stall it slsps 2nd really hard. some times it also stalls when im slowwing down to a stop, and it stalls alot when im doing a three point turn. what is the problem???? ive done alot of things like new o2 sensors new air idle controll sensor,  coolant temp sensor,and otherthings. please help!!!!!
ANSWER: I had that happen to my Camaro before but it was after I did a huge cam. The motor wasn't getting enough air so I had to drill the IAC hole bigger.

In your case I would guess the IAC pintle hole in the throttlebody is clogged or dirty. Worst case scenario the IAC motor is bad.

Remove the throttlebody and clean out the IAC hole at the bottom on the mouth of the TB.

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QUESTION:  ive allready put a new iac sensor (motor?)and cleaned the hole theres got to be some thing else

Answer
When was the last time you changed the fuel filter? Change the filter and hook up a fuel psi guage to the schraeder valve on the fuel rail.

Does the fuel psi drop when the car is about to stall? If so its either a clogged filter or a bad fuel pump.