1993 Chrysler Town and Country Please help my SICK van!

The PROBLEM is that my van seems to skip, cough, hiccup, stall, or whatever term seems appropriate and sometimes would even cut off. In the beginning, it only did a few times and clear up after driving for a little while. At first, I thought I had gotten bad gas, so I used gas treatment. This seemed to help. I drove it to Illinois from Alabama with only a little trouble out of it. The van only sat for a day before I drove it again and now the problem is even worse! The jolting is really bad. I've noticed that the speedometer will jump from 60 to 20 or even 0. The cold air gets almost hot. These happen when the van "skips". Two days ago I also noticed that sometime when I left off the gas a whistling. There are NO LIGHTS on to check the engine. I can left off the gas or press the brake and it will stop "skiping". This problem is not ALL the time, but it seems like it's heading that way fast! Today on the way taking my son to speech therapy was the worst of all! To top it off the serpentine belt came off. We fixed that! Got home and tried to leave again and now the waterpump is leaking and there is water on the plate around where the head gasket is. I can't afford to take it to a pro, but my husband can fix most anything on a vehicle. He's stumped as to what the ailment is, and so is everyone else that we have talked to! Please help us!