Spark is good, we pulled the wires while running amd there is good spark; almost got knocked on our back side a couple of times due to getting a shock.
Sorry, had a chuckle out of this one... been there, done that.
There are quite a few different things that can create symptoms.
Sounds like you're getting some good tips to check so far. My first thoughts were vacuum leak, fuel supply, crossed wires, plug gap (since fire is good to the plug...) check fire at the plug ignitor.
Also comes a question... Did you redo the heads? valve seats ok etc.? A compression test might answer this.
Hope this is a minor issue, quickly resolved.
Jerry
