The past few weeks I've been having idling issues. When I'm stopped at a light, the car at times idles low at around 800 rpms, then can jump to 1200 rpms. This morning at a light, it dropped to about 400 and was shaking like it was going to stall then spiked to 1200 before coming back down. At times when I take my foot off the brake, sometimes my car jumps forward ready to take off before I hit the gas. When I got home this evening, I put the car in park and it was idling between 1200-1400 rpms. I had it at the dealership last week and they suggested a dirty throttle body. My husband cleaned it yesterday and said it wasn't dirty. This idling issue is getting worse each day. Any ideas?