So after shifting my car will jerk real hard about 20% of the time. just over and over until i let go of the gas and lightly press it again.

Usually if i try to accelerate fast it doesnt happen. this happens at around 2-3.5k rpm

I was told it could be spark plugs among a few other things but it had a tune up about 3 months ago

 

try your cleaning your IACV/FITV
also, when was the last time you replaced your air filter?

 

You jumped timing

 

Hm, well i plan to replace the timing belt soon.

How much does that cost to do generally?