have a 1980 Chevy camper van with a 350cid ran exeptionly well from Edmonton Alberta to Las Vegas Nev. were I filled up and immeidiatly began to expierience missing, low power,poor acceleration until I mashed te throttle to kick open the secondaries in order to get up to speed, cruise would not maintain speed so had to constantly use secondaries to exellerate. air cleaner is ok plugs are clean wires test ok, pulling wires off dist cap indicats every second cyl is dead at idle. does this unit have an EGR valve and could this be the problem???

 

You should move that load of Fuel to a separate container, and get some from a known good source. IF, that doesn't correct the problem, you can always pour it back into the Tank. Be sure to get it all out of the Tank to be sure it's a Fuel problem.

When you put new Fuel in the Tank (just a couple gallons) it may take four or five minutes of running, to completely access the fresh Fuel.
Drive it at least 10 miles.