Car is a 54 chevy with a stock 235. Headers, single Leakchester BC converted to manual choke, Pertronix unit. Outside temp here is about 65-80 F so my lazy ass hasn't hooked up manifold heat - yet. Starts well and runs like a dream till she's good and warm, say 20 mins into driving, then starts to miss on accelleration some times. Seems to get progressively worse till it does it on all but the mildest takeoffs. Its still driveable after about 2 hours, but it doesn't gimme the ooh-ahs like it usually does. I figured its gunna have to be fuel or spark - whats your take on it?