Sounds like a bad coil pack. The coils tend to break down under load, so they could work fine at idle or low speed, but at higher RPM, they may give out. I can elaborate on the Electromagnetic properties of a coil if it would help you out.

Couldnt hurt to try that.

Metal Thunder Dragon, AKA Matthew Blakeley Electronics Tech '99 Mercury Mystique LS - Loaded '96 Ford Explorer Sport - Standard '90 Ford Taurus L - Rusting silently in the back Iraq-Land of the lost!