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You have a bad or out of adjustment shift position switch. Cylinders 2 & 3 are inactive when the switch is closed. When the switch opens it allows all the cylinders to fire. You can check it with an ohm meter. The switch is where the control cable attaches. There are two switches, the other is a shift cut out switch for ease of shifting.
There are two switches are you sure you are looking at the correct one, it is the innermost.