I believe that is the transmission downshifting. Mine is fairly jerky when stopping, I think my tranny is telling me it's getting tired. I have asked for problems, the car is either idling or it's floored!
Try shifting into neutral when coming up to a light and coasting, also leave it in neutral when sitting, I bet the feeling goes away. I don't see how the fan could affect too much, it's electric, it shouldn't be able to lug the motor down any really. The A/C can a little, but it still shouldn't make it jerky.
If you haven't done so yet you might want to think about changing your transmission fluid. That could be the ticket. If you take it to a shop make sure they use Mopar ATF+4 fluid, not Dexron/Mercron III or you'll be back in short order.
Hope that helps,
Ben
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2001 Red PT Cruiser Limited, 16" OEM alloys, Airaid CAI, Screamin' Demon coil and Livewires, some shiny stuff inside, Alpine deck, Alpine four channel amp, Alpine PLT5 sub, Hertz speakers in 4 corners, Keystone ram air hood, 6000k 55w HID high beams, 6000k 35w HID fog lights, new stone chips every day to add character.
2007 Suzuki King Quad 700 4x4 for when the road gets bumpy.
