It'* a 2003 grand prix GT 3.8L 155k, recently had upper and lower intake manifold gaskets done, then right after that had tranny cooler erupt in radiator had GM dealer replace radiator, upper and lower hoses, thermostat and two cooling hoses. Now my issue is stalling, the car literally just shuts off randomly when at idle only,never when actually driving but if I stop at a light, or put in park to run in store it shuts off, I've tryed stepping on gas when it'* about to die and it still shuts off... I'm a jam with this, I just replaced the fuel tank pressure sencor, the fuel pressure regulator, and IAC sencor (idle air censor) and twice today it died on me, need some help/suggestions

If it started doing this after the dealer made repairs, then they are responsible for fixing it.

Scan the car for codes. See if there are any stored problem codes.
What brand of IAC do you buy? Was the throttle body cleaned, while they had UIM off?

When it was at the dealer it was scanned for codes but it was there for a transmission/radiator issue thats what I paid for. Codes P0440,P0446,P0453,P1441. We're on the sheet given to me, couple days after leaving dealership my check engine light disappeared on its own, and isn't displaying anything now... in past week alone I myself removed throttle body cleaned it, replaced the fuel tank pressure sencor, fuel pressure regulator, and the air idle control sencor... and it'* still dying at idle

So NO it was not cleaned when the manifold gaskets were replaced.

I wonder if the ignition may play a role here.
Maybe the gaps are out on the spark plugs, ignition wires new?
Was a Delco IAC Used?
Fuel filter new? Any Readings of fuel pressure from a gauge available?

Spark plugs were replaced about 6 months ago, better spark plugs. The IAC used I don't believe was ac delco but I'll call autozone to ask tomarrow. Ignition wires haven't been touched. And do not have a Guage available.

But the gaps on the plugs would they allow for the car to almost always restart after waiting 10 minutes... so frustrating having it only die randomly, but only at idle

The IAC does effect or controls the idle. Try another IAC use a Delco, see if that fixes it.
A misfiring engine could also stall at idle. Wires would not hurt if they are original.
The plugs are relatively new so, I think you are probably good there.

Duralast is brand of IAC sencor I got, 1 year warranty, put that on monday, fuel filter did 2 and half weeks ago.