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High idle vacuum, replaced pcv valve already.

Hunson.aberdeer
Hunson.aberdeer
in Ford S-Max Club

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2007 Ford S-Max 2.5t (same engine as st225)
I have a problem with having high vacuum pressure about -25/30 on idle, complete loss of performance. WOT gives me about 7psi of boost max where as it used to go 20/25psi. 

Initially I was getting slight blow from engine and small amounts of oil being lost and searching showed pcv valve was probably at fault. I changed pcv valve and car immediately jumped to high vacuum and I assumed this was good. Now I have big loss of performance.
Plugged in to snap-on unit, no codes for anything but ECU was struggling with air fuel trim quite badly.

Changed entire oil filter housing as new pcv was deemed suspect faulty part. No difference. Also replaced spark plugs, foam elbow from block to oil filter housing, rubber pcv hose from valve case to filter housing.

I have suspicions.

MAF
MAP
BCS

I have also ordered intake-to-block gasket incase it's that.

Also have a decat to go on just incase cat is blocked. 

I haven't managed to find any boost leaks visually and even got some t clamps for most pipes.
Anyone able to help identify where to look before I start just throwing money at parts.
Thanks 😊

TL;DR
not pcv valve but big vacuum still, performance suffering. What to do?

IMG-20240801-WA0003.jpeg

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