Many thanks.
It's 12v and does have a ballast resistor.
The truck did run perfect when I bought it so whatever adjustments/modifications the previow owner did, they worked. He was a mechanic who owned his own shop and was very diligent about doing everything right.
Will just start again from square one and follow his instructions. He was sure it was the timing since the problem happended when you tried to accelerate and there was a load on the engine.
Thanks again
