resistor cause miss??

[swedishsteel]

I have a '36 coupe with 221LB with Eddie Meyer heads and dual carb high rise manifold with two 97's, four speed S10 tranny, 2.75 nine inch rear end. Runs super, except when it gets to operating temp and pulling hard around1000-1500 rpm (just guessing, no tach) it bucks and misses, until it gets wound out a little and then runs strong 'til I shift, then bucks and misses some in the next gear. I turned down the distributor brake one turn and it helped some, but it didn't ping to start with that I could hear. Being it doesn't do it when the engine is still relatively cool, (short run time) I'm wondering/asking if the resistor under the dash could cause weak spark after it gets hot?? Basically stock 6 volt system. I have rebuilt coil by Max and rebuilt distributor by Bubba, so pretty confident the problem isn't there. Accelerator pumps are new and working good. Pulling the choke out doesn't help, so I'm pretty sure it's spark related. Thanks for any ideas. Rod