i have owend a xm for the last 4 yearsit is a 1992 XM SI 2.0L injetion and i wood like some help/addvice on a supention prob as the back gose down within 3 minets of the engen stoping

Sounds as if you have an internal leak, may be a rear suspension unit or the rear height corrector. Any internal leakage will find its way back to the LHM tank so I suggest you go to the LHM tank and disconnect the return lines one by one with the engine running. Look for a noticeable flow of fluid and then check the hydraulic diagrams to see which component is connected to that return line.

Derek