My blazer runs perfectly except after it rains. After it rains it just turns over, no fire. If it does fire up she chugs like she's misfiring. I have changed the cap and rotor. What's next?

 

Next I would do the plug wires.

 

Check the ignition coil for arching by the coil wire. If the tower on the coil pack is cracked it will arch worse when wet. You can use a spray bottle with water to narrow down if its the coil or a bad plug wire. Its best to do when dark (and not raining) , just spray around the coil, distributor, and plug wires. It will likely be obvious when you find the culprit (cracking noise, rough idle etc).