Extended Crank and Rough Idle?

I have a 99 camaro with the 3800 series II engine. I has a bad extended crank. When it sits for about a day or more it starts imediatey. It will also start right up after I fill the tank full of fuel. This seems to be the only two consistent things, other than that there isnt any real pattern. After it takes a long time to start it idles rough for about 10 seconds. It always starts eventually and has never stalled. After that it runs perfectly fine. There are no codes present.

It has recently had

Plugs and wires
fuel filter
air filter
PCV valve

Any ideas on what this might be?

Thanks,

Derek

Since you say it starts right up after filling the tank, try just removing the gas cap and putting it back on and see if this cures the problem. If it does then you probably have a bad negative pressure relief valve on the tank.