I have all of these same problems. I've been trying to solve this for 7 years now. I can live with it on some things, but I find my middle finger is lacking compared to my index. On very fast passages with constant string crossing my middle finger eventually begins dragging because I don't get the same amount of attack. I think the two problems are related.
Here's one that drives me nuts... This is played in constant eighths 196 bpm.
--------3-3----------------------
----3-3-----3-3-5-3-1-1-3-3-----
1-1--------------------------1-1-
----------------------------------
or this @ 200 bpm:
----------------------------------
-------------2-2--------------2-2-
----2-2-5-5----------2-2-5-5-----
3-3--------------3-3--------------
-------------2-2--------------2-2-
----2-2-5-5----------2-2-5-5-----
3-3--------------3-3--------------
-----------------------------------
-----------------------------------
----4-4-7-7-4-4------2-2-5-5-2-2-
5-5--------------3-3--------------
-----------------------------------
-----------------------------------
-----------------------------------
----2-2-5-5-2-3-5-5-5-5-5-5-5-5--
3-3--------------------------------
-----------------------------------
-----------------------------------
-----------------------------------
3 (whole)--------------------------
I've almost resorted to using a pick on these lines.