The engine will rev up fine, then I put it into gear and it will miss and back fire. I changed the plugs,the fuel filter and added dry gas, it is still happening

What engine???

I would also change the cap and rotor and check the timing.

just putting it into gear at idle when when you try and get on it. Could be a lean backfire and not really missing. Just went through the same thing, sure acted like ignition but it was a lean backfire, rebuilt the carb and found a little snot of rtv in it.