Falls on its face at 15psi

My TC generally runs and idles great, but I have one troubling issue. When I get on the gas hard the engine pulls very hard right up to 15 pounds of boost, then it acts as if someone has put their hands over the air filter and it stumbles and falls on its face. Boost never builds much over 16 pounds as all of this is happening. I have a Gillis valve set per the installation instructions. I have a K&N in the fender well, 3" downpipe, 3" exhaust all the way out the back. I have intalled a boost gauge and a fuel pressure gauge on the A-pillar and have verified that my stock boost gauge is accurate. I have noticed no noticible fall off of fuel pressure. It builds smoothly right along with the boost (up to 15 psi). So, am I running out of fuel delivery capability with the stock pump? Or am I running out of ignition energy? The one area of this engine I have not gone through is the distributor (PIP, TFI, etc). I do have a new cap and rotor and new wires, however they are not Ford parts. I have noticed no detonation. The knock sensor is still hooked up at this point. Near as I can tell I am running 10 degrees of initial timing. Any help would be appreciated.

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88 TC
Salvage yard long block doing fine
5-lug / big brake M-2300 kit coming soon
3" ATR downpipe / 3" single with Dynomax 3" Super Turbo muff
Fuel pump, adj. regulator coming soon
Boost and fuel pressure gauges are now in and functioning on the pillar
Want to build an Esslinger aluminum headed V8 eater

Well, you might not be noticing any detonation, but the KS might be. You can maybe desesitize the KS by wrapping the threads in teflon tape, or try disconnecting it for a run up to boost and see how it reacts. I know mine was overy sensitive due to general engine noises (which these motors have a lot of) and I just had to disconnect it to even get it to boost past 10psi. With the stock fuel system, I would look at maybe trying the teflon taoe approach to see if that changes anything..

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Any connection between your reality and mine is purely coincidental..
83 Pseudo-Coupe, 87 Ranger (soon to be 2.3T), 84 XR7, 86 XR4 and 62 Mercury Monterey (old n slo)
NATO Member

what do you mean by fall flat on its face? i think you might be having a problem like i had well one of the many i am still trying to get over. how are your vacume lines and the big hose from your vam to the turbo? i was told to check thoes i did, found some soft ones and replaced them. i had a major air leak and i never thought it would be the rubber hose between the turbo and the intercooler but it was prodecing a leak because i replaced it and it doesnt leak anymore.

Thanks for the input. I will try with the KS disconnected to see if that makes any difference. The feeling I get when I hit 15 psi is that either timing is being backed out or air supply is being compromised.
I have new IC hoses and all others have been inspected or replaced so I don't suspect anything of that nature.

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88 TC
Salvage yard long block doing fine
5-lug / big brake M-2300 kit coming soon
3" ATR downpipe / 3" single with Dynomax 3" Super Turbo muff
Fuel pump, adj. regulator coming soon
Boost and fuel pressure gauges are now in and functioning on the pillar
Want to build an Esslinger aluminum headed V8 eater

Disconnected KS and it runs great all the way to redline. I guess it was a bad sensor or just overly sensitive. Thanks for the help guys.

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88 TC
Salvage yard long block doing fine
5-lug / big brake M-2300 kit coming soon
3" ATR downpipe / 3" single with Dynomax 3" Super Turbo muff
Fuel pump, adj. regulator coming soon
Boost and fuel pressure gauges are now in and functioning on the pillar
Want to build an Esslinger aluminum headed V8 eater