slow crank when warm

1992 chevy s10 4.3. Slow cranks after it is warmed up and been driving, I put a new starter on, checked the battery load, and everything seems to be fine. Any ideas? Starts right up in the morning, just after it has been warmed up and drove it will crank slow then fire. Thanks for any input.

hit up your local auto parts store for a full charging system test. they'll do it for free. sounds like a dead cell in the battery.

On slow crank?
Is the starter turning slow or engine just slow on starting?
How is base timing?
And as viggy58 said how is the battery?
How may amps is starter pulling hot start?

For slow cranking diagnosis, this might help:
http://www.aa1car.com/library/voltage_drop_testing.htm