I'm losing my mind and nobody can help

Ford says there is no prob but even my buddy who's driving my car has noticed this change...
I have a 98 contour SVT with 167,000KM. I have occasional powerloss which happens after some time of driving...it can happen on the street or highway. Doesnt matter. The engine will gradually feel more and more sluggish until I feel I've lost at least 25 to 30% power. The secondaries still open and the car still revs right to redline but does so slower and the engine tone sounds a bit deeper. I can also hear a little more 'wooshing' sound through my KKM filter (from the inside of the car). Basically sounds like the motor is straining. Oh and the really strange thing is that the gas pedal will not feel crisp and firm. It will feel softer and more mushy...almost like its attached via a thick rubberband. When the car runs well and fast, the pedal is nice and firm and crips response. I've checked the linkages and cannot see anything wrong there either.
Now the thing is that the car does this only sometimes and almost never when the engine is still kinda cold. Its definitly not heatsoak because its way too much powerloss and even did it today at 12C weather. I dont have any fault lights to telling me anything is wrong. My last dyno (6months ago) gave me 164HP at the wheels but it was not misbehaving then. I also went to the track once and managed 15.4 @ 89.5. It felt ok that day too. I guess I could have showed up without a full tank of gas in the car.
I've got:
-new plugs gapped at .054
-wires are about 1 year old - stock ford ones
-upper and lower intake pulled and cleaned manually with new gaskets installed
-fuel filter is about a year old (I always run at least 91 octane)
-had a motorvac done 6 months ago when I first got a hint of the prob.
-replaced the IMRC motor a while back when it first started happening thinking maybe its not opening the secondaries right.
-the cat is also about 6 months old...I thought the stock car was plugging up. Got a larger 3" catco cat. No change
-ypipe is stock but modded...picked up a few ponies but has nothing to do with the prob
-KKM filter
The only things I can think of are the O2 sensors and maybe a fuel pump? They are both stock units but I get no fault lights. Only thing that I've had is once I got a check engine light but when away in the middle of driving and once or twice I've seen the airbag light flash 3 times then stop and repeat. Turning off the car and then on again stopped that.
Its driving me crazy. Anyone know what the hell is going on? Oh and I always run synthetic oil in the engine as well so I try and take care of it... Even reading the plugs, they are all the same shade of a slightly rusty to brown colour but not too dark.
Anyone can offer any suggestions would be great.