I remember from the past some discussions about this happening frequently when pads were replaced. Didnít make sense to me because all youíre doing is pushing fluid backwards in the system into the master cylinder. But if memory serves, Bob (FireM) explained that over time, moisture accumulates in the system, and with it being heavier than brake fluid, water and any rust or other trash sinks to the lowest part of the system - IOW, the calipers. When you push the pistons in with new pads, all that moisture and crap gets blown back up the system and can cause problems (how Iím not exactly sure - maybe in the master cylinder). And thatís why Bob always said to open the bleeders when pushing the caliper pistons back in - to get the junk out *there* rather than push it back up the system where it can cause problems.
Also, sometimes you can ďfixĒ things like that by activating the ABS system to get any trapped air out of the ABS loop. I had read of that, and dang if one time I replaced my pads and had squishy brakes afterwards, and normal bleeding didnít help. The next morning, on the way to work, I had to do an ABS-activating panic stop when I was late seeing a school bus stopped in front of me. For whatever reason, my brakes were solid after that.
You can activate the ABS less drastically by slamming on the brakes on ice/snow or gravel. Might be worth a try. I know some people have tried that and it worked, and others tried it and it didnít accomplish anything. Might depend on exactly what the cause of the soft pedal is. If itís a bolus of air trapped somewhere, it could be simply that the induced shock to the system dislodged the air and it bubbled up into the master cylinder reservoir.
Sorry for the rambling. Just some things that might help.
'98 LXi - Later Concorde gages (black w/ chrome rings)/'99 LX - LHS gages (white) - HIR bulbs