Through the majority of my tc's life it's idled rough. Especially apparent in drive throughs, RPM will go from 1k RPM all the way down slowly to about 800RPM and then dip back and forth from 500 - 800 sometimes staying as low as 500. this is when the car really starts to shake and make noise but for some reason shifting into park or neutral will slightly increase the RPM and stop the shaking, sometimes it consists. Any ideas how to fix this? My guess at the moment is a dirty idle air controller but i'm not sure how to clean it given location and that it's electronic. Any help appreciated.

 

That's just what they do. Some say they've had success adding grounding or performing basic maintenance, but nothing I've done has made much difference. The rpm's dip when the cooling fans kick on so perhaps increasing the voltage would help but not sure how to go about it.