Starting to REALLY dislike my Insight

Hi all. 2000 Manual, less than 60k miles. not the original owner. LMPG about 54 but i have been getting about 62 for my ownership.

The car is running very bad these days. i am not sure if herky jerky really encompases the whole picture. the battery seems to be OK as far as charging goes.
I will be driving along say 30 in 3rd. light pressure on gas. the car will then start to really jerk...enough to physically move myself and my wife back and forth in our seats. the rpm gauge is sitting there fluctuating up and down a couple of bars.
it will go away if i floor it (assist) or put the clutch in.
also, the car seems to be having a lot of difficulty with power. it seems to need the assist to go ANYWHERE. keeping the car at 65 on the freeway is a challenge, unless i want to be getting less than 50mpg.
tires are approx at 43-44psi (all 4) and are about 1 year old. the car has AC but we never use it.

i would hate to take it to the dealer and tell them to fix it when i have no clue what is wrong with it.