When truck is running the starter want's to engage not good for the flywheel or starter i think it might be the ingnition switch but not sure need help /???

Hi! there,
well, possible cause engaging starter while
running there is a short circuit on your starting
system wiring.
check on ignition switch after starting and
engine run normally,possibility after
cranking and release the key run
engine normally there is short occurd on
solenoid relay.if defective replace this is
mounted separately from starter motor.
usually on near engine there a fuse and
relay box.

you mention you changed starter motor
and no change,there is starter solenoid
attached directly to starter motor
assembly this to move the plunger pinion
gear that will hook the flywheel to turn.
after cranking and normal engine run.after
that the plunger pinion gear will disengage
by the supply from solenoid relay.so you
must check your solenoid relay circuit.

have a nice day.dont gorget to rate me
thank's

Ignition switch