2005 buick lesabre

My 05 buick lesabre is idling wrong. It fluctuates
up and down, if i dont feather the gas it will shut
off completely, it starts and runs, when i give ut
gas its like someone is kinking and un-kinking the
fuel line, it wont go past 4000 rpm without
stuttering or spit sputtering, ive replaced the plugs,
the wires, ignition control module, all 3 coil packs,
the crankshaft positioning sensor, the cam shaft
sensor, the harmonic balancer, the heat shield for
the balancer, and now its not even throwing a code
for me check but its still jerking at a stop, and the
rpm fluctuates up and down, sometimes stalling
out completely. Someone pleaaaase help any
advice would do, ive disconnected the mass air
flow sensor and it didnt change anything, ive
unplugged, while it was running, all kinds of
sensors and nothings changed, everything is
plugged back up and its still the same, i feel like im
soooo close to fixing it, but i cant pin down what it
really is.