car won,t run consistent

I had a similar problem with my car. It was running right at the verge of being too lean. It was OK mid day but when the air temp started to cool off and the engine wasn't at full operating temp it would stumble leaving in the later rounds but would MPH Ok and sometimes a little faster because of the lean out at top end. I raised my jets 2 sizes and now don't have a bit of trouble leaving and any engine or air temp.

Chuck