Weird acceleration issue

This doesn't happen often but usually occurs on a hot summer day especially in traffic, usually only in 1st or 2nd gear. I'll clutch in, get in gear, clutch out,accelerate as normal and for no reason the car will take a nose dive (think a 16 yo learning to drive stick). When I come to a stop the rpms will rise by about 200 and come down then the "instant mpg" needle will bounce as well. More pronounced with the ac due to heavier load I assume. Does this sound like a maf or tps issue? MIL is off, no internal fault