94 S-10 SS starting problem

The engine starts fine when its cold but after running for a while and trying to restart it, the starter drags its beginng to get worse almost to where it doesn't wont to turn over at all. I thought it was the solenoid for sure so I went ahead and replaced the starter and solenoid figuring after 170,000 its about time for it to be replaced. Checked the battery for voltage which checked out fine (12.5vlts) but still have the same problem. Any one have any ideas what else would cause this?

Check battery cables pos and neg.
Have the battery load tested. And charging and starter system tested.
A good hot battery should read about 13.2 -13.5 volt 2.2 volts for each cell.
And check engine base time.
If timed to fast it will cause starter drag.
How many amps is the starter pulling/drawing when hot?

i know when i had my 94 s10 SS it was the EGR, or the coil pack.