03 4.4 starter problems (kinda)

[Shang]

03 4.4 with 125k on it.

Starter began to randomly not engage the flywheel. So, I could hear the starter spinning, but the bendix gear not working. I replaced the starter with a reman and it worked four times, then had the same problem except never engaging the flywheel. So, I thought I had a bad starter out of the box. Replaced it again, and same thing. Worked for a day, then no more engage. I tried jumping the car from another thinking maybe batt voltage was low, but same problem.

So, at this point, looks like it's not a bad starter, not a bad battery.

Anyone have a similar issue? Anyone have a schematic of the car start system?

Thanks for any help!