2003 Pontiac Grand Prix GT jerking 2nd to 3rd

This has been happening in the same place in my
commute for the last few days. I  get off the
backroads and accelerating to around the 45mph
area, it feels like the transmission is slipping. It
jerks and shudders, then the Trac Off light comes
on. I pull over and let it sit for a minute and usually
it behaves the rest of the way. No trouble on
freeways or under 40mph on backroads. I put
some Slip Fix in it to no avail. Mom thinks it's my
timing chain. Dad thinks it's a misfire. I did check
each wire on the coils and there's spark all around.
This is my $200 car and I don't want to spend a ton
to fix or diagnose it. Thoughts?