Man I was on my way to work today and my Formula started to sputter real bad. Thought to myself that the dist. was going out. But on the way home tonight it ran fine? I think it might have been the cheap gas I put in it and the temps outside were in the mid 80's. It also does this when it rains out but only for a few miles, kinda like the K&N filter gets water in it.

 

It's possible the humidity/dampness is causing parts of the ignition to arc. Run it in the dark with the hood open. Look for arcing at the Otpi, the coil, the plug wires, as much of the plugs that you can see, particularly the metal shields. Spray a fine mist of water on the parts and look again.