tranmission noise

i think it might be the torque converter, but theres a nasty vibration when im in i would assume thrid gear and about 45-50 mph, if i hit he gas it goes away but if im at a steady speed its a really bad vibration what is that and what shoudl i do

i have a 1994 dodge grand caravan 3.8L AWD 150,000 miles

try changing your transmission fluid, see what happens. Use Mopar ATF +3 for your van. What you are experiencing is torque converter shudder. It's not too serious, but for driving comfort, that Mopar ATF+3 helps smoothen out that shudder you feel.

45-50 is a little high for torque converter shudder, usually that happens between 35-45 mph. It could be a bad CV joint, I guess, though those usually are OK when driving steady and shudder when accelerating . . . can't hurt to change the fluid like theFREAKnasty82 says.