problem.....

i have a 96 taurus 3.0L v6 and i jus put a new motor mount like a month ago but since then about last week i started hearing the engine hitting agains something every time i accelerate fast or when it changes gears from 1st to 2nd. it also makes the noise when i put it into drive from park or reverse....the noise is gettin to me i tired findin out what it is but i havent had any succes.....anyone knows what it could be or if uall had have a simalar prob.?? thx