Misfire?

Guys I have a 68 200 with petronix kit weber 32/36 dual out headers and the rest is pretty much stock. Yesterday took it for a ride and it backfired one the started running rough. So I took the top off the carb checked the float and needle valve everything looked ok. Cleaned the carb with some carb cleaner reassembled fired it over it has hat feels and sounds like a miss at idle . The idle is fluctuating but if I take it out and drive it she feels normal. Am I looking at a bad petronix or am I looking at a carb problem?

Things to check to find your miss:

1. Compression test, all cylinders need to be close approx within 10% to run smooth.
2. Vacuum leaks at the base of carb even check the throttle shaft if worn etc.
3. Dirty or bad electrical connections and poor or missing grounds
4. Battery connections, weak cell or cells, low charge, low alternator output.
5. Bad plug wire, plug, or distributor cap (carbon tracking) dirty or worn posts
6. Weak coil output
7. Distributor advance and or a very worn distributor (upper bushings)

The idle is fluctuating but if I take it out and drive it she feels normal. Am I looking at a bad petronix or am I looking at a carb problem?

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As far as testing if the Pertronix is the cause it's easy enough to take it out and reinstall a set of points and see if it still misses. I am thinking its more of a electrical problem than carb but I am not there to see it. Good luck

So I think I found my mis. The throttle shaft on my secondary is leaking vacuum. There is a company that sells a throttle shaft bearing kit that seals the shaft.Anyone try it?

Common problem with some Weber's and copies that they made in certain countries. Never tried it but it could work. Back in the day I would just replace them with a new one.