1997 Jeep Laredo Shaking when stopping

Shakes or Wobbles problem
1997 Jeep Laredo 6 cyl Automatic 120000 miles

I have a 97 Jeep grand cherokee laredo. The car starts fine no problems, warms up fine. I put it in drive and it drives fine. When I come to a stop sign or a stop light the car will idle almost down to zero and shake like it is going to stall out. The car does not stall out because right before the rpm hits zero it gives it self gas and idles back up. Wait about 5 more seconds it will do the same thing over and over until I let it go. It also seems to be getting, according to the sensor that comes in the car telling how much mileage per gallon the jeep gets, worst then usual mileage. It supposed to get around 15-16mpg but the sensor is now saying around 5. It seems like the accelerator also doesn't respond as well as it should. Any help will be greatly appreciated!