Long Term fuel trim value?

Using a scanner, I see that I have a high long term fuel trim number - 25%. From my research it seems this should be about 10%. At present I do not have any trouble codes.

Here is what I have done so far. After each action I monitored long term fuel trim for changes while engine is at idle.

1) Checked and cleaned PCV valve - it rattles when I shake it.
2) Removed and plugged EVAP purge hose.
3) Removed and plugged brake booster hose.
4) Clean MAF sensor (MAF wires and Intake temperature thermistor).
5) Cleaned throttle body.
6) Checked for vacuum leaks - valve cover, intake manifold and hoses. Used brake clean and water squirter.

I have run the engine to 3,000-4,000 RPMs for 10-15 seconds and I see long term fuel trim go down below 10%, which points to vacuum leak but not successful in locating it.

Any ideas? Fuel delivery seems okay when I go WOT but have not pressure tested pump or cleaned injectors.

BTW, I can send you pdf of scan tool output of parameters if it helps.