tranny trouble
 

97 crown vic p71 w/ 118k mi:

Im wondering if anyone can help me here. Im short on money and my transmission is whack. I need to know if it would be less costly to get a new tranny for my car, or have my current one fixed.
heres the symptoms:
surging at low rpm's and low speeds
too much power during half throttle shifting screeches back tires as if theres too much power hitting the rear.
when shifting from 2nd to 3rd at full throttle(i think its that shift its around 50 mph), it goes to shift up but it cant for about 3 seconds. and it screeches the tires there too.

all other times while driving the tranny is perfect.

help me out!!!!!