Would a bad series resistor have any bearing on the way the car runs. Could someone elaborate on this? Would it have any bearing on the way the car runs when it gets warm?

Sure it would. If it is allowing too much voltage to the coil, it could cause the points to fail prematurely. Too little and it could cause the spark plugs to have a weak spark.

I personally don't see how this would affect the engine more when it warmed up. I tend to go with the fuel problem, but (my theory) I wonder if you have injector problems that are masked by the richened fuel mixture when cold.

Still think you need to have a chat with the shop.

Chuck

I agree with Chuck on this.
99.5% of the time a resistor fails open circut. If there is a resistance deveation, there wound be a notable history of premature failed points, or gradule decline in loss of power. Sounds to sudden to be resistor failue.
Regards,
Bryan