Car runs fine but lost 4 lbs of boost

[Kini]

I have a 1993 LaserRs Fwd Turbo, totally stock 90k miles, 5 speed. The car normally made about 11-12lbs of boost on the factory gauge. (i know the factory guage doesn't actually measure boost, but am using it as a baseline. The car lost 3-4 lbs of boost from one day to the next. The car runs fine, starts easily, idles smoothly, doesn't miss, revs to redline (although because of less boost it's pretty flat up on top). I had the car checked at my mechanic. According to their boost gauge it is only making about 9-9.5 lbs of boost. The waste gate opens at 13lbs. The exhaust is not plugged. The intake and exhaust have both been checked with nothing found. The fuel system tests out to spec. They even called Mitsubishi techs who had no suggestions. I've searched the forums and have not been able to come across anyone who had the same problem. If this question has been answered before I apologize for missing it. And thakns in advance for the assistance.

Gene

 

[93EclipseGSX]

maybe a bad tank of gas ? our cars are sensitive mine would boost different all the time due to air temp change and many other factors on stock soleniod. could be many things.... find the problem or is it still messed?

 

[Kini]

I've been thru many tanks of gas. The boost now is always low, regardless of temp etc... I and my mechanic have checked and tried everything we can think of. Thanks
Gene