surging and stalling in closed loop

[jaded93atx]

The title about says it all. I am getting no codes or ce light except for the 556 fuel pump code showing that it has stalled. Once warm it doesnt want to hold an idle while driving unless I feather the accelerator to get it to"catch" the idle. Even when on the Highway as I take my foot off the pedal on an exit ramp it will drop down to 500 surge to 1200 then fall back down and stall. Anytime I goose it the engine revs then without catching idle it stalls. Other than that aggravating issue it isnt missing or acting sluggish. Ive swapped out the MAF and checked the IAC they are OK. The O2s are new and mileage is OK It does have some oil in the wells but as of yet its not miss firing. Again I'm getting no codes or CE light. Since it only happens once in closed loop it seems sensor related but with no codes popping up I cant figure it out. I'm not having any hard strarts and on the highway theres no issue as long as I keep pressure on the pedal.
I'm not a SHO newbie and have worked through a variety of issues with this car but this one has me stumped. In the 4 years I've owned it, because of coresponding codes Ive replaced O2s, MAF,TPS,VSS,TSS, cats, CPS, CID,ECT,and the DPFE, resolving issues as encountered. It has no intake mods and I'm not running a K&N.
Thanks in advance for any insight thats better then mine.

 

[jaded93atx]

Update to my origional post... I took it on the interstate and it hauls *** just fine when I let off the accelerator and let her coast for a minute, I get a short CE light then it goes out. The code I pulled is for MAF output voltage lower than expected. I keep getting this code no matter how many (4 so far) MAFs I swap out... with the same driveability issues. Is there something I am overlooking that would also cause that code and corresponding idle issue?

 

[jaded93atx]

FIXED...thanks for the replies though....really!

 

[40BelowSummer]

what was it?

 

[jaded93atx]

My IAC was stuck open, it must of been triggering the MAF code after heavy acceleration and letting off the pedal by letting unmetered air into the intake via the valve from the heavy vacuum...Thats my theory anyways. It was also stalling more frequently anytime it was warmed up and I let off the pedal abruptly...It was getting pretty dangerous especially around turns.I had cleaned it with carb cleaner like I found in searches a while ago but that only cleaned the chambers, not the part of the shaft thats concealed by the plunger inside. This time I pulled it and and hooked up a 9 volt battery with a little speaker wire and touched the leads to the IAC leads, first I got nothing then I reversed polarity and I felt the plunger try to move. This let me know that the solenoid ws still good. Then I sprayed it good with cleaner and worked the plunger with a screwdriver by pushing up on the spring then back down gently on the plunger...until I could see with a flashlight that the shaft had no more build up on it and the plunger move easily. Once I put everything back together it was like night and day. No more surging, stalling, or CE light after heavy decceleration with corresponding MAF code.
Sorry this so long I just wanted to be specific for anyone with these troubles, I know I've been trying to chase it down with no specific answers for awhile now. Hope this helps some of you out, and saves you the 80-100 bucks for a new IAC, BTW my IAC is the one piece design.