sounds like what i had i ended up changing the throttle positioning sensor on the throttle body.
i would change that and the fuel filter
the filter first then the tps.
i had to replace that in the pic it is for the spark relay or some thing like that it is for a 97 thunderbird. it seems to help it i also did a tune up and change the wires as well.
all in all check the fuel filter and the tps first let us know if you could narrow it down