Engine cuts in boost!

[New92]

Ok gang, Ive waited forever to post this thinking Ive missed something in the threads but I dont see an exact match to my issue so...

The pertinent details:
'92 SS 5mt, Magnecore wires, desnork, mug, 1g dsm bov recirc., Eaton MBC, SAAB tmic, sti turbo back no muffler.

I installed my new K&N drop in and took her for a drive. I immediately began to notice a problem with the power delivery as I hit partial to full throttle. It would stumble as though Im hitting fuel cut. Also my idle rpms jump up to around 2000k. I get a CEL of course for a bad IAC and so replace it. I clear the ecu of all cels and run d-chech to be sure and all is well. RPMs at idle drop back down to normal range and I go for another drive. Now my issues are as follows:

-Under any boost 1psi or more I stumble and hesitate, current boost set at 5 psi
-Acceleration from a stop will cause stumbling without extra gas
-Partial throttle is ok but at mid to full throttle the same stumbling occurs even if positive pressure is not yet achieved

So my only idea at this point is that I am somehow maxing out my MAF? It is the common metal variety not the plastic unit.

The car seems to smooth out slightly at higher rpms 3000k + but definitely exhibits the worst at low speeds and low rpms. Ive not noticed any spikes or dips on the vac/press gauge other than when it starts to stumble under boost. I believe the turbo had been rebuilt before I bought the car and what little I can see of the exhaust and intake housings and guts would support that claim so in short I am stumped. There is so much info out there about this problem but it all points in multiple directions so I guess Im just looking for a solid lead as to where to begin diagnosis and repair.

Thank you for looking and I appreciate any help a knowledgeable member can provide.

Ben

[smh0101]

Check for boost leaks... mine did something similar before I found the leak

[Fkyx]

Yeah... I had a problem that sounds similar to yours, and it turned out to be a disconnected vacuum hose.

[bmxkelowna]

like the other have said, it sounds like the vac line to the MAP sensor is not connected

[New92]

Thanks guys. I had done a cursory check of the vac system but Ill give it an in depth exam. I appreciate the feedback.

[mexicanzero]

that exact problem used to happen to me when my y pipe of my intercooler blew a hole in it it would be pretty much closed. so check for significant leaks or some of the bigger vacuum lines being unplugged. actually you're still seeing some boost so it wouldnt be as big of a leak as mine was so maybe look to make sure clamps are tight and all the small vac hoses are hooked up.

it wouldnt hurt to clean you mass air flow sensor and throttle bore either

it could possibly also relate to fuel or spark so check your plugs and wires to make sure they arent fouled or the gaps are too big or small and that the wires havent rubbed against anything wearing the outter layer away.
and if you can test the power your coil is putting out that would help
and maybe check your fuel pressure. is your pump unusually loud at all? is your fuel filter old?

-Alex

[New92]

Dont know about the filter. The pump is rather quiet so I feel confident that the issue isnt there. I did swab out the TB but did not mess with the MAF. I used a thin coat of RTV black on the TB and IAC seats and went over all of the hose connections to the MUG, BOV and IC. From what you all have been saying it must be a fairly small leak so I think I may just have to start replacing hoses until the issue is resolved. I do have T type clamps on all turbo, IC and TB connections so I feel confident that the issue is not there. Ill keep you all posted.
Thanks again,
Ben

[New92]

UPDATE:
So I tore apart my hoses and connections and replaced suspect lines and secured fittings and clamps. There was a marginal improvement ie. I no longer stumble off the line and I can hit about 4psi at highway speeds in the higher gears. So of course you were all correct, I do have multiple leaks and finding the rest is I guess just a matter of time. On that note has anyone found a good replacement for the plastic lines connected to the PCV system??

New problem, the ambient air temp is now averaging in the mid to high 30's and I threw a new set of codes: 44, 35, 24. And strangely, when I insert my key into the ignition without turning it I hear a high pitched whine. This noise will continue once the car is started and running and stops the moment I pull the key out. Im sure it is electrical as the turn signal and engine rpm affect its pitch and tone. Any ideas?