I concur with rkent, this is very likley a vapor lock issue, wich would be affected by the barometric pressure a great deal, ie. the weather. However I had a similar problem with my 142E w/efi but it turned out to be worn point cam lobes causing the timing to error, when this first happened to me I thought it was the little screen on the fuel pick up being plugged. Besides an electrical tune up never hurts.