try some exercises to go from a string to another
when i have my 4 string was very hard to do the same thing, the E string was not as solid as the D or A but if you do patterns will help you a lot
in the progresive bass concepts john myung explains the technique that he uses
try to do some pentatonic scales with the 3 finguers that will help you a lot
and for the 3 finger use this pattern
321 and 3212(for go down fo another string)
in
www.stevedigiorgio.com
steve explain this technique
try also do scales in 2 string with the 2 and 3 finguer so they can be as fast as you 1 , 2 techinique
ok
any questions im glad to help you