my 99 svt has been exhibiting the same problems, and I've checked the usual culprits. First did it a a month ago. Then everything was fine but now its done it the 3 out of the last 3 days. Though if I leave it and come back in an hour it will start.
Just cleaned the IAC.
If its turning over strongly I would assume that indicates a strong enough battery.
I've been getting a CEL 136 code but that comes and goes and I didn't think it was relatd since that is one of the rear Oxygen Sensors (sensor is fairly new, so that's probably a wiring issue.
