It sounds to me like ignition misfiring under load. There is a possibility that they disturbed the 1, 3, 5, 7 plug wires and they(one or others) are not fully connected. It could also be carbon tracked wires or plugs, causing the spark to find a path to ground. The plug and the plug gap, are rather high resistance, and it is not hard for the spark to chose a path of least resistance. I would say if you don't find something obvious, like #5, or #7 plug wire loose, then replace the plugs and wires. I prefer o.E. Replacements.
Monday, October 4th, 2010 AT 11:25 PM