Idle / off throttle problems

[blabla]

I've done research and solving of my idle problems before (two of them - one being with the throtle position sensor - and the other the Idle control vavle was gunki so I cleaned it and put it all back together and voila) - but this time it's a bit special.

Let's start from the begining.Yesterday night it would not idle if you put the car in neutral will cruising - when coming to a stop it would not idle either.I use to be able to get a proper idle if I let it in gear until 900rpm or so and then put in in neutral. But puting it in neutral if I was at over 1500 rpm was a guaranted stall.

I thought it was the idle control valve again so to test that I put the A/c on to see if the problem would disapear - but it does not change anything.

Today I recieved my walbro - put that in - take the car for a spin - the problem is the same but there is something new.When letting go of the gas a certain way - the engine stumbles a bit and then it engine brakes normally.

What do you all think ? Putting the walbro raised the fuel pressure before the fuel pressure regulator... so I'm guessing I'm in for a new fuel pressure regulator possibly ?
Modified by blabla at 2:18 PM 4/17/2008

[Rucca]

How do you figure turning on the A/C rules out your IAC? Sounds like you may have multiple problems but I'd start with checking for vacuum leaks and IAC.