Western Members - Engine hard to start.

98 Camaro SS with 80,125 miles.
About 80k miles is when this started happening. The engine takes almost 3-4 seconds for the engine to start. Before, as soon as I turn the key, the engine would fire right up. The hard start would happen when ever it wants, warm or cold. Had the battery checked and the alternator checked @ auto zone, all fine they say. But the volt meter in the car sits just above 13. Maybe fuel fuel filter? I always gas up with 91 octane 76. Any ideas?? Head lights aren't dim. But I did noticed last night that the head lights dimmed than back to normal. Twice already. I have an optima battery. Thanks for the help.

check the grounds and start with the fuel filter. check engine light? how are the plugs?

check the grounds and start with the fuel filter. check engine light? how are the plugs?

I was thinking about the fuel filter, too, but not sure if that's it, but heck, easy fix, why not change it? Plugs? I think I should change them. It's maybe been awhile. No check engine light. Any other things I should check??