Your choke could be richening the idle/transfer circuit when the engine is warming up. Then when the engine is warm and the choke is open, the engine could be seeing a lean spot off idle and during tip in.

I always adjust my pump cam linkage when the engine is idling and with a flash light. I lean over the engine "just enough" to see the front squirter while shining the flash light on that squirter. Then I move the linkage and watch how soon the fuel starts to pump out. If the fuel does not pump out as soon as I move the throttle, then I readjust it and check it again. I move the nut about 1/8 of a turn until I see fuel.

What pump cam color do you have? Do you have a hollow squirter screw with the 42? If not, then you won't see much of a difference in pump shot larger than a 37 squirter.
Note: A 42 is a large squirter. Maybe it is time for a pump cam swap.