I have a 2000 & whenever the rpm's dip under 2000 my car starts to shake, almost violently. I've replaced every coil, every coil plug, reset the ecm, even tried using a fuel injector & nothing has changed. I've already spent over $500 on this car for this one problem! Anyone have any possible solutions?

 

Have you checked for CEL codes? Maybe you should do a compression check.

 

I haven't yet. I'll check that when I can

 

Bad motor mounts could cause this as well

 

If it's not throwing a code you probably have a vacuum leak. Even a small vacuum leak will cause a very rough idle that goes away at higher RPMs.

Get a cheap can of "brake parts cleaner" from the parts store and use the little red stick that comes with it. With the car idling, spray it around your intake and vacuum lines. When it hits the leak you'll hear the RPMs rise and smooth out for a second. Keep narrowing down the area with short sprays till you find it. It's most likely just a rotted line.

There's nothing under the hood that will be damaged by the brake cleaner but don't get it in your eyes. Wear glasses because it can hit and spray right back at you. It won't kill you but it's painful in the eyes.