"messing with the air intake"   - all i did was place my hand over it.  

Anyway - i disassembled the carb and had a look at everything (Clymer manual is pretty good ) and after reading the two last posts I'd agree that it's the diaphram or the slide (i'm hoping/thinking the slide).  I didn't get out my magnifying glass but there were no glaring holes in the diaphram.  I did clean off the slide with some gas as there was some build up on it.  It is running fine now, but I'll be going on short trips for the next bit to see if it acts up again.  If it does I'll start  at the diaphram.  Thanks for all the help and suggestions guys.