Engine problems bucking, loss of power?

Be running great then goes to crap. Suddenly when u accel, she'll break down bucking, loss of power, motor be misfiring, and will vibrate. Next day she good for awhile then goes back to crapping out. Then later all good again. Have new fuel injectors, spark plugs and rail, replaced throttle position sensor, maps heat sensor, have checked several times for vaccun leaks, replaced trans mount, u joints, replaced main cat, when run codes, one time nothing, then next day misfire on 3, next day it'll show throttle position sensor which a new one had been put earlier that which at that time ran great for 50 miles then crapped. This has cost me money, time, not having transportation, stress and down right ugly. This jeep has ran great and does not even burn any oil. I need help finding problem