Alright. I went and inspected the adjustment on the pump arm and it seemed to be adjusted right where the arm would start to get depressed instantly when moving the throttle.

Now this is something I have always wondered about but the accel pump arm has a little play in it. In other words, it can be pushed down a bit (maybe .030-.040) from its resting position before I 'feel' resistance like its pushing the diaphragm.

I had the throttle arm adjusted so it was holding the accel pump arm just 'south' of that resting position but maybe .020-.030 from where it began to feel resistance. There as no gap at all between the throttle lever arm and the accel pump arm. I went ahead and backed off the adjuster nut 1/2 a turn or so which puts more tension on that arm and brings it where it will start to feel that resistance as soon as the throttle is moved.

Does that sound right? Hopefully this makes sense...

So anybody care to explain why if this was misadjusted, why it would be crisp while the engine was cool and get a bog when warmed up? This particular circuit should operate identically hot or cold, right?

Thanks for the suggestions so far.