This reminded me of a non-related but possible concern.
Look at the primary wire feeding your ignitor (distributor) - mine was contacting the engine mount and rubbed through to bare wire causing erratic voltage and at times an open circuit.
I fixed it when I had a memorable experience on I-70 East of Columbus Ohio - the danged wire separated, stopping spark at the plugs but after coasting for some time (still drawing fuel, filling the exhaust system with fuel vapor!) it reconnected and BOOM! blew my muffler apart when the engine restarted. I thought for sure I'd lost the engine.
Check that wire - sporadic spark gives some of the same symptoms as fuel issues.
"other peoples junk, is something or other" - Militarypotts 02/07/2011