misfire and backfire

[My'73]

When my car is cold it idles and runs fine. After it warms up it misfires and backfires while I'm driving but it will have a normal idle when I stop and put it in park. I did a tune up about a month ago but the problem just started New cap, rotor, plugs, wires, fuel filter and air filter. Please help

 

[Chuzz]

Sounds more like a timing issue than anything, but I'm not a mechanic. What type plugs did you use? I always recommend using OEM plugs, meaning what came in the car when it was new. A LOT of vehicles don't run that well on aftermarket plugs. Bosch are the cheapest out there and I've never had a car run worth a crap on them.

 

[My'73]

Yeah I'm going to pull the plugs out and see how they been firing