2005 Kia Optima no power

OK, first let's start off by saying when I bought the car 2 years ago the check engine light was on and the RPM gauge didnt work. Now, about 3 weeks ago I was driving at about 60 MPH and all of a sudden boom loss of power dropped down to about 40 no matter how many times I mashed the gas it wouldnt accelerate then all of a sudden it picked up speed out of no where. When sitting in park irs very sluggish and the engine jumps back and forth bad real bad. Ive replaced coil packs spark plugs iac valve ive cleaned throttle body ive checked mass air flow and cam sensor the only thing I havent checked is crank sensor and oxygen sensor only because I dont know where they are. If you can help me in any way itll be appreciated.