Sensitive brakes on 1997 4runner

I've noticed that my brakes are very sensitive lately. I'm wondering if it has anything to do with the differential oil that got on the rear pads when the rear seals blew out about 3 months ago. The shop cleaned them off but they still looked oily to me. I'm also wondering if it is parking brake related as one or both of the bellcranks are frozen (there's no cable sag, but one of the stops has a gap and the parking brake doesn't work). Or is it brake fluid related. I am years past the point of needing to replace the brake fluid and bleeding out the old fluid.

I've never understood how drum brakes work and the interaction with the parking brake, so all thoughts appreciated. TIA.

Replace the shoes that are contaminated with gear oil, along with all the other shoes on the rear axle to keep the braking straight. Fix the parking brake mechanism. Flush your braking system with fresh fluid.

I've noticed that my brakes are very sensitive lately. I'm wondering if it has anything to do with the differential oil that got on the rear pads when the rear seals blew out about 3 months ago. The shop cleaned them off but they still looked oily to me. I'm also wondering if it is parking brake related as one or both of the bellcranks are frozen (there's no cable sag, but one of the stops has a gap and the parking brake doesn't work). Or is it brake fluid related. I am years past the point of needing to replace the brake fluid and bleeding out the old fluid.

I've never understood how drum brakes work and the interaction with the parking brake, so all thoughts appreciated. TIA.

You just listed 3 things wrong that need to be fixed !

With drum brakes, the parking brake uses mechanical means (lever and cable) to move the shoes instead of hydraulic means.

Ok, did all three items and it made a huge difference-great! The only thing I'm not sure about is the emergency brake. I've never owned a vehicle where I've used the emergency brake. It grips, but not that much. It seems like it should hold better. Do they self adjust over time somehow? or do I need to do something else? tia!

It will auto adjust to some extent if you apply it several times while backing up.

There is also an adjustment for the e-brake cable, typically underneath the vehicle, approx under the pass seat.

Don't expect much in the way of stopping ability. It is meant to keep a parked car from rolling on a hill, not stop it while going at speed (although some stopping is much better than nothing in an emergency).