I had an 04 FJR that would occasionally give me a hard start, which is part of the reason I got rid of it. It would usually happen after sitting for a few weeks, even on a battery tender. My S10 gave me one hard start after the one and only time I filled it with high octane gas. I burn regular now, with out any problems. One time when it was really hot outside, it acted liked it wouldn't start, but I went WFO and it fired. When its hot out this is my starting procedure. Kill switch off, turn key on, flip kill switch to run and immediately hit the starter button. When I do this, it turns over a couple more times than usual before firing, but when the injectors fire, the engine is already turning and will fire before they have a chance to flood the cylinders.
All of this could be BS thinking on my part, maybe a few of the more knowledgeable readers will chime in.