The high side pressure seem a little high. The fact that spraying water on the condenser made the pressure drop makes me think you aren't moving enough air through it. Maybe a good external cleaning of the condenser and radiator will help. Remove the upper clips that hold the radiator in and lean it back and look between the cond and rad and make sure there in nothing between them. Spray the condenser and radiator with a strong cleaner (greased lighting, etc), let it soak for a few min and rinse with a water hose. This may sound silly but make sure the aux fan is running the correct way. It should blow toward the rear of the car. I saw a problem of a fan running backward and the a/c high pressure would run wild. It didn't seem to bother the engine but sure drove the A/C crazy. I use Freeze-12 in both my cars with high side running about 200 lbs on a 80 deg day. Low side around 28. at 1500 RPM. Booth cool good.
Stay Cool
Paul

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84 500 SEL (307,xxx miles)