89 olds starting problems

I have a89 cieara 6cyl. it will start after sitting for a few hours but if you turn it off and then try to restart even after shopping etc it wont crank at all. but after sitting for about 3 hours starts right up. the time to get it starting has been getting longer. we just replaced the ignition switch which seemed to help for a few days but now its doing it again. help

Welcome to AF, check for current at the purple wire at the starter solenoid when cranking, if good, the starter/solenoid is NG, if none you must back track to the neutral switch on the trans and all the wiring from the ign sw. to the neutral switch to the starter, make sure the battery connections/grounds are clean and tight also.