starter keeps trying to engage when engine is running

i have a 96 gmc the starter keeps trying to engage when the engine is running i put a new ignition switch in it a relay

do you have a remote starter on the vehicle?

I'd see if it still tries to engage the starter with the trans(if automatic) in gear. You could pull the starter relay in the underhood fuse/relay panel and possibly swap it with the A/C relay. You should also inspect the starter for loose metal of any kind that could possibly jumper the cable from the battery to the solenoid post with the purple wire