2002 Dodge Intrepid PLEASE HELP

HERES THE DEAL, MY TRANSMISSION IS ACTING UP. ONCE THE CAR HEATS UP IF YOU EXCELARATE PAST 50 MPH ONCE YOU DECELARATE, (SAY STOPPING AT A RED LIGHT), ONCE THE MPH REACHES ABOUT 15 MPH THE CAR WILL JERK. AFTER I STOP AND THEN GO TO EXCELARATE AGAIN, THE CAR SLOWLY DRAGS, BUT IT'LL GO, BUT THE RPMS IS LIKE PAST 4 SOMETIMES TO 5.

THE THINGS I HAVE DONE IS I TOOK IT TO A DISCOUNT AND IT HAD 4 CODES. NOT SURE OF THE CODE NUMBERS BUT I KNOW THEY SAID THE SPEED SENSOR NEEDED TO BE REPLACED, A NEW TRANNY FILTER, SOME TRANNY FLUID AND THE O2 SENSOR. SO I HAD THE INSIDE AND OUTSIDE FILTERS REPLACED AND THE FILTER AND TRANNY FLUID. IT WORKED ON MY WAY HOME THAT EVENING BUT THE NEXT DAY THE PROBLEM IS STILL THERE. I AM AFRAID TO TAKE IT TO A TRANNY SPECIALIST JUST YET CAUSE I AM A WOMAN AND I DON'T WANT TO BE TAKEN ADVANTAGE OF SO I THOUGHT I'D DO SOME RESEARCH BEFORE DOING SO. ANY GUIDANCE YOU COULD PROVIDE IS GREATLY APPRECIATED.