starting issues! need advice
 

i have a '96 blazer 4x4 4.3L and i'm having issues with starting. i recently did a tune up (plugs, wires, new distributor assembly, egr valve, all vac. lines, etc.) the starter is ok but i have to cycle the key at least three or more times (sometimes less) in order to crank. when it doesnt start right away i hear the starter motor spin but doesn't fully engage flywheel it seems. when i cycle the key i usually remove then re-insert key adn it will turn over. I'm wondering if the issue is either ignition switch or if i need to shim the starter. any advice on this issue would be helpful! thanks