Car vibrates in gear at idle - 2005 Buick LeSabre

Idle could be set to low .

What is the RPM while in gear? Too low and it will vibrate. Also check for weak/broken motor mounts which will cause a vibration in gear

When you are in gear at idle with your foot on the clutch you have placed an axial load on the crank which is pushed forward in the main bearings against a thrust bearing. I suspect a failing thrust face on this bearing as it only works under a clutch release load. The only other point that is under load is the clutch throw out bearing but if that is failing you should be hearing a tinny type of rattle when you have the foot on the clutch

I would have to be tghere to run tests, this is a hands on type of problem.

Wow you change everything, TPS was right thing to do and so is the Idle air control,and MAF and EGR, fuel pressure, So it idles high then some one tried to defeat the stall in gear? Even if there is a vacuum leak creating high idle it shouldnt stall in gear, , What color is the transmission fluid? when in gear in drive step on the acelerator pedal to maintain idle to prevent car from stalling. Just enough to maintain let say 1100RPM. Is there a vibration? I mean a torque convertor vibration. Torque convertor stall are common an GM and Nissan,very rare do I ever see it on Ford. I really belive the IAC is not getting power and is just been adjusted manually, cause I know its not the transmission, At idle in gear pull the plug on the idle Air control does it change in idle setting? If it doesnt change in Idle setting the adjustment that was use to control the setting lower the idle to its normal setting. Plug the idle air control in then.The idle air should change the setting. If it doesnt its not getting the signal it should.

check engine and gear box mountings

VIBRATION CAN BE CAUSED HARMONIC CRANKSHAFT BALANCER.BAD TORQUE CONVERTER ON TRANSMISSION CAUSE VIBRATIONS.

Check to make sure both headlights are tight,,,when it rattles at idle go feel the headlight and hold it and see if the noise and vibration goes away,sometimes the headlight has too much clearance and causes a massive vibration,,if thats not it try...loosening all the motor mounts and rock the car back and forth and them retighten them,it reseetles the mounts and sometimes fixes the issue,,also check the lower engine and trans mounts for wear.

IF GEAR SHIFT SHAKES THEN THE TRANSMISSION MOUNTS COULD BE BAD. HOPE THIS HELPS. GOOD LUCK

Have you tried checking the exhaust heatshields?