1994 jetta/rough idle & auto trans slips
 

i just bought a jetta 2.0 eng. auto trans. the car has a rough idle, the guy i bought it from said he had just changed the timing belt and thought it might be a tooth off. when i accelerate the car drive good and has power, but at an idle and taking off its rough...??? also it has a 4 speed auto trans he said that drive was actually overdrive and 3rd gear would be drive. it runs fine in third gear and shifts fine, although the rpms are a little higher. when in drive it is like it is in nuetral...?? any help would be appreciated....