I have a 01 pontiac grand am with a 2.4L . My two biggest problems are at while in gear at idol the rpms drop between 600-700 and the engine shakes hard, vibrating my interior as well.The problem also gets worse when I cut on the ac fan or use my windows, like its a electrical current problem. The second problem is now that I have changed bank 1 sensor 1 O2 sensor. Now anytime i get to speed and let off the gas my rpms jump up and down a few times before going back to normal and you can feel the surge. I have done a full tune up, checked multiple sensors including maf,map,pcv,tpc,cps, and more. I have checked for vacuum leaks, my motor mounts are good....I have asked multiple gm specialist, and several other mechanics. No one including myself can pin point my single or multiple problem, so any help would be appreciated.