I have had my Voyager for about 3 years now, I just changed out the sparkplugs and wires and did the oil filter, I also had to change the radiator because the thermostat went out a few months ago and it overheated and killed the radiator. well for about 2 months after I replaced it everything was fine. then I let my now Ex boyfriend drive it, and when I got it back it did not seem to have any power and it has steadily gotten worse. It seemed to run fine if I did not have it on the interstate, but when I give it more gas it sputters and acts like it is not getting any. I have black smoke comming out of the tailpipe, and it seems like there is a little puff of smoke or steam comming from the back of the engine, down really far, close to the exhaust. now it sputters like mad and does not want to go anyware at all. it will still run, but it wants to die unless I give it full gas, even just idling. I know a little bit about cars, but this has me baffled, and to be honest I am dreading the suggestion of replacing the head gasket becuase I cannot do that on my own. Any help would be appreciated.

check your carburetor, make sure the choke is not closing up the airway; also make sure you don't have any garbage in your fuel that would cause a problem as well.

Sounds like a blown head to me . . . check your compression.