Chevy S-10 Starting

I have a 2000 Chevy S-10 USED pickup.

From day one everything is great except, when I start my truck the first thing in the morning it fires right up. After that it always starts, but I have to churn it for several seconds longer than my initial start.I have had several scans done but no results, lastly I had a crank sensor installed that according to a GM tech would solve my problem, no luck.

Anyone have this same problem or ideas please advise.