Chevrolet Repair: 2000 astrovan wont start, question pool, vapor lock

Question
I have a ? I have a 2000 astrovan. It used to be that it just wouldnt start when it was damp. So i replaced the distributor cap and rotor. (non gm) i was told that could be the problem. So all together i have replaced the distributor/cap/ plugs / wires. I got a new oil change and a fresh tank of gas.   I got good fuel pressure and good spark. But it has its days when it just wont start. I also replaced a sensor on the bottom of the crank right nder the front of the van i forgot what it was something with a magnet in it. I tried spraying ether to get it to go and no luck.

Answer
Are these days it won't start typically wet days?  If so, could be a bad coil.  

Fuel filter been done?  

Is it HOT on the days it won't start?  If so, could be vapor lock.  Could be this anyway.  Next time it won't start, take fuel cap off.  Try again.

Next time it won't start, try to determine if it is a problem with spark or fuel.  Then let me know.  I found this question in the 'question pool'.  When you update, direct it to C J S.