19year old starter motor emi

[Rvolvos]

Don’t want to hijack this thread, but I have similar problems.
When cold car starts okay, tachometers goes from zero to 700rpm
Starting when hot long cranking and tachometer spikes / jumps up and Down.

Fabricated a bracket to replace the worn broken bracket at the Rh corner of Engine to keep the wires up and away from the starter. The wire harness containing the crank and cam position wires routes over and behind the starter( perpendicular to the starter) and ties in into the front wire harness. 2nd option from PGills list?
I also removed the positive lead from the wire harness away from the cam position sensor.

I did not make any difference, still long cranking and tachometer jumping up and down.

Only solution is to replace the starter with a good used one what hopefully produces less EMI.