Keep your windshirt dry if you can. It's not rain gear and is proably the first thing you will reach for if and when the rain quits.
I would l look for a new jacket. Be careful about cleaning it.
Look for rain shells with good ventilation features: pit zips, back cowl vents, big pocket openings with mesh linings, and snaps or seperate Velcro tabs on the front storm flap. That last items allows you to close the front of the jacket with the zipper open and venting through the gaps in the snaps or Velcro. A jacket with those features won't weigh 7oz. Too bad. Suck it up and put up with the extra weight for the features, or get wet— or maybe I should say wetter.
Or try a poncho
The Northwest Coast Native Americans delt with it by wearing capes of shredded cedar bark, probably the original breathable rain gear. Not much of a fashion statement, but interesting to think about. Maybe we need some sort of "shingled" rain gear. Imagine a Cuben jacket with four courses of overlapping Cuben fabric, bar tacked every three inches or so. A pull-over would be easier to make I think. The shoulders, upper chest and sleeves could be one piece to eliminate a top seam. Of call it a gill jacket.
An hour long thunder shower followed by glorious shafts of sunlight and warmth is a completely different thing than three days of drizzle at 50F and no direct sun. Even your brain gets soggy! There isn't a free lunch on that. Having a spare dry base layer is one way to deal with it.