Lindsey Janae Mercer

We bought our first Jeep Grand Cheroke Laredo 2000 in August, and things were perfect (for a used car), and then my husband took the Jeep out for errands on the 26th of September and things started going downhill very fast for the health of the car. This day, the car died on him while driving. It took 3 mechanics to tell us it was the crankshaft sensor. Got a new one. As soon as we were driving it out of the shop, it started to overheat, with boiling water and steam coming out of the resevoir. The mechanic checked everything out again and said there was no reason for the fan to not work (though it was not coming on?) so he hooked up a cable from the fan to the positive side of the battery for us to manually start the fan so it will keep the car from overheating. It was okay doing this for awhile but now it seems as though we are constantly pulling over while doing errands because of the jeep overheating. When pulling over, we can see steam coming from the motor itself and not just the resevoir like before, and there is also steam coming from the exhuast valve. It smells like something is burning when pulling over. It's not strong but it's there. The engine has a weird sound when overheating, like it's choking maybe? Last night I noticed that the oil gauge was almost at 0, we just did an oil change on the 15th of Septmeber! We live in a city/residential area, and usually don't go over 30mph most days. What is going on?
Another thing going on, which may or may not be related, is when we are accelerating and get to about 15mph, the jeep starts to jerk, like it doesn't want to go, and after every 10mph or so it continues to do the same. When doing this, the rpms jump around. I mentioned it to someone else and they thought that it could be the gas filter being clogged. What is going on?
If anyone can help shed some light on what is going on with our cherokee, and tell us how we can fix it (or if we should sell it now!) we would really, really appreciate it! Thanks!