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2002 Mitsubishi Galant Vibrates at stop lights

I am having issues that i think are related to the transmission.

when i am stopped and the car is in drive it starts to vibrate significantly however once i start moving again the vibrations stop.

Switching to neutral or reverse also causes the vibrations to stop.

I am thinking that somehow the transmission is not fully disengaging when the break is pressed like it is supposed to but i may be way off on this

More than likely it needs a IAC cleaning or throttle body cleaning. MAF cleaning would also be suspect. When is the last time plugs were changed. Is the check engine light on. This car also has a timing belt. Has it been changed?

The acronyms they burn @_@

Timing belt and spark plugs were replaced earlier this year

also if it was a issue with misfiring due to a load on the engine it would also occur when the transmission was in reverse as this also puts a load on the engine considering the issue only occurs in drive on the lowest gear i am doubtful that its the engine itself because a misfire would remain noticeable at higher speeds if not prevent the car from accelerating properly it has also been in the shop quite recently for routine maintenance and no problems were found with the engine which is why i still suspect a transmission issue

Have you done a trans fluid and filter service?

ill have to check but i dont think it was done recently

If you let off the gas the Idle Air Control valve controls the air getting into the engine.

Rough idle on an older car is usually caused by worn/collapsed engine mounts, especially on an old Mitsubishi. How old are the engine mounts? I don’t think new transmission fluid will help.

also replaced last year due to a loud banging noise

actually a lot of things were replaced last year on account of the dreaded 100k blues

but its really not idling rough it idles just fine unless its in drive

What did you replace last year, the idle air control motor or all four engine/transmission mounts?

Check engine light on?

Usually when the trans on this car fails, it starts with a flare and then it just gets worse.

That’s a good diagnostic point you make OP that the vibration only occurs when stopped with brake applied at idle in forward gears D and 1, but not reverse. I’m with you, with no reverse involvement, it doesn’t seem like it could be an engine-firing problem. Except for this idea: If you had problems both with the engine and the mounts, it’s conceivable the vibration would be most apparent in forward gears, b/c the force the engine applies to the mounts is probably different in forward vs reverse gears. So maybe you have both engine and mounts problems.

just the Engine mounts

I think @Barkydog 's idea, a proper transmission service, is probably a good place to start. What about the transmission fluid level? Does it check out ok?

how do i check that

That procedure is probably in your owner’s manual.

Warm up the transmission/car. Engage the parking brake, hold the brakes and shift through all gears, then leave the car in neutral and then check the level on the dipstick. I don’t know why Mitsu has you check the level in Neutral and not Park, but that is the way they want you to do it.

Do you have a photograph showing the location of the dipstick for the transmission