2000 blazer starting problem

Have a 2000 blazer has intermittant starting problems.  Some days it will not start cold, other days it is fine.  Turns over fine but acts like no gas.  Mechanic says pump is working and has pressure.  All it takes is about 10 minutes of a small electrical heater blowing on the cabarator and it starts right up.  Could it be the fuel regulator.

Have you tried either having a professional fuel system cleaning done or just over the counter fuel system treatments?  Sounds like you may indeed have sticking poppet nozzles when cold, but replacing the spider should be considered a last resort after cleaning has been attempted.

Have been running fuel system cleaner with every tank the last few weeks.  Seems to happen more often on damp or wet days.   Had plugs and wires and tune up done but did not help. 

When the tune up was performed, did it include changing the cap and rotor?  The fact that it does it more on damp/wet days leads me to believe it is a spark issue.

yes cap and rotor were replaced