I"m not sure I agree with you regarding carb ice. While it may not have
been your problem, I've had carb ice in the J-3 that resulted in more
than just a drop in RPM, the engine was doing next to nothing. Each
time I've gotten carb ice it has been with not visible moisture. I
think the visible moisture thing is just an old wive's tale. There is
no need for visible moisture to get carb ice.

Does the C-152 have a fuel filter? In my Mooney I have a couple screens
but no "filter" per say. I guess the difference is that the screens (in
theory) are for larger stuff and not as likely to clog.