Automatic transmission

So I'm having a problem with my 2002 Chevy Silverado not
shifting properly.   When accelerating to 30mph, it's still
running a 3k rpm's.  I have to let off the accelerator, re apply
and then it will shift.  After getting up to 45 and up to 65,
the rpm's climb  to about 4k to 6k rpm's.   I've replaced both
knock sensors which was the original issue.  Now it's still
operating at the same copacity.  What else could the
problem be?  I've changed the transmission fluid amd filter.   
A friend of mine hooked it up to his computer and he said
it's running fine.