Loss of low-end power

[Steve Sherman]

Well a fuel and a water pump later and my 86 5KTQW is back to running
again.

Everything seems fine, but one thing I noticed was that there seems to
less power at low rpms than before these changes.   I'm pretty sure that
the timing belt is on right, with the cam mark aligned right with the
crank.  But I did not check all that carefully as to the alignment when
I took it off, so perhaps the PO had moved the cam timing a notch?
Might that have given more low end power?

Also I notice that the rpms tend to undershoot the idle rpm and then
climb back up to it when I release the throttle.  So perhaps with a
fresh/ more powerful fuel pump the mixture needs to be adjusted again...

Any thoughts from the listers as to what else migh cause a loss of power
below 3K rpms?

TIA